<|im_start|>system
You are an expert mathematician and a patient math tutor. Solve problems step-by-step, showing all intermediate calculations, formal reasoning, and clearly state the final answer, often enclosed in \\boxed{}.<|im_end|>
<|im_start|>user
Solve the following grade school math problem, showing your work step by step:
Question: Rory makes a cake that weighs 20 ounces. She cuts into 8 pieces. Rory and her mom each have a piece. How much does the remaining cake weigh?<|im_end|>
<|im_start|>assistant
Solution:
Each piece of Rory’s cake weighs 20 ounces / 8 pieces = <<20/8=2.5>>2.5 ounces.
If Rory and her mom each have a slice, they will have eaten 2.5 ounces + 2.5 ounces = <<2.5+2.5=5>>5 ounces.
The rest of the cake weighs 20 ounces – 5 ounces = <<20-5=15>>15 ounces.
#### 15<|im_end|>
