<p>Agent is a buyer of gasoline in the black market if his consumption of gasoline exceeds 20 i.e. $G &gt; 20$, and he buys $(G-20)$ units from the black market in this case. So, his budget constraint is $R + 20 + 10(G-20)=100$</p>

<p>Likewise, agent is a seller of gasoline in the black market if his consumption of gasoline is below 20 i.e. $G \leq 20$. In this case, he sells $(20-G)$ units in the black market. So, his budget constraint is $R + 20=100 + 10(20-G)$</p>

<p>To conclude, his budget constraint (in all cases) is $R + 20 + 10(G-20)=100$.</p>

CC BY-SA 4.0
2018-05-05T02:00:41.653Z
Thank you sooo much.  Thanks to your helps, I not only understand the answer but especially also understand how I should think when I see such type of questions. Thanks a lot. 
studentp
CC BY-SA 4.0
2018-07-11T01:25:58.833Z
Dear Amit, I hope you’re doing well. I have two questions, I solved,  but I stack at some points. When you have time, I will be happy if you solve. Many thanks.
studentp
CC BY-SA 4.0
2018-07-11T01:26:04.067Z
First question https://economics.stackexchange.com/questions/22722/consumer-theory-signaling
studentp
CC BY-SA 4.0
2018-07-11T01:26:17.437Z
Second question https://economics.stackexchange.com/questions/22720/duopoly-game-asymmetric-info
studentp
CC BY-SA 4.0
2018-05-05T00:47:07.117Z
2018-05-05T00:47:07.117Z
Amit
<p>Della’s utility is $U(G,R)$ </p>

<p>G is the consumption of gasoline per week</p>

<p>R is the the consumption of other goods </p>

<p><a href="https://i.sstatic.net/W3rxD.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/W3rxD.jpg" alt="enter image description here"></a></p>

<p>Just help me to write down budget constraint. </p>

<p>I think that </p>

<p>$$R*1+(G-20)*10+20*1=1000+10*X$$</p>

<p>where </p>

<p>X is the amount of the gasoline that she sell on the black market. </p>

CC BY-SA 4.0
2018-05-03T14:38:49.980Z
Budget constraint is simply : $R+10(G-20)+20=1000$
Amit
CC BY-SA 4.0
2018-05-03T19:23:37.710Z
@Amit but the agent also sells gasoline purchased. How can we show this in the budget constraint? Your budget constraint doesn’t tell this statement.
studentp
CC BY-SA 4.0
2018-05-03T19:24:50.303Z
@Amit then how can we find how much she consume and how much she sell?
studentp
<microeconomics><game-theory><utility><consumer-theory><self-study>
How to write budget constraint if the agent sell the goods that buy
studentp
# How to write budget constraint if the agent sell the goods that buy

(Asked by: username_0 on 2018-05-03)

Della’s utility is $U(G,R)$

G is the consumption of gasoline per week

R is the the consumption of other goods

[![enter image description here](https://i.sstatic.net/W3rxD.jpg)](https://i.sstatic.net/W3rxD.jpg)

Just help me to write down budget constraint.

I think that

$$R\*1+(G-20)\*10+20\*1=1000+10\*X$$

where

X is the amount of the gasoline that she sell on the black market.

**Tags:** microeconomics, game-theory, utility, consumer-theory, self-study

> **Comments:**
> **username_1**: Budget constraint is simply : $R+10(G-20)+20=1000$  
> **username_0**: @username_1 but the agent also sells gasoline purchased. How can we show this in the budget constraint? Your budget constraint doesn’t tell this statement.  
> **username_0**: @username_1 then how can we find how much she consume and how much she sell?  

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## 1 answers

### Answer by username_1 on 2018-05-05. Score: 3 | Accepted answer

Agent is a buyer of gasoline in the black market if his consumption of gasoline exceeds 20 i.e. $G > 20$, and he buys $(G-20)$ units from the black market in this case. So, his budget constraint is $R + 20 + 10(G-20)=100$

Likewise, agent is a seller of gasoline in the black market if his consumption of gasoline is below 20 i.e. $G \leq 20$. In this case, he sells $(20-G)$ units in the black market. So, his budget constraint is $R + 20=100 + 10(20-G)$

To conclude, his budget constraint (in all cases) is $R + 20 + 10(G-20)=100$.

> **Comments:**
> **username_0**: Thank you sooo much.  Thanks to your helps, I not only understand the answer but especially also understand how I should think when I see such type of questions. Thanks a lot.   
> **username_0**: Dear username_1, I hope you’re doing well. I have two questions, I solved,  but I stack at some points. When you have time, I will be happy if you solve. Many thanks.  
> **username_0**: First question https://economics.stackexchange.com/questions/22722/consumer-theory-signaling  
> **username_0**: Second question https://economics.stackexchange.com/questions/22720/duopoly-game-asymmetric-info  

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