boy sells a book for rs. 630 he gets a loss of 10 %, to gain 10 %, what should be the sp?  Choose the correct choice from the following:
A) 430  B) 450  C) 550  D) 770  E) 660
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">630 / (9/10)</gadget>
<output>700</output>

<gadget id="calculator">700 * (1/10)</gadget>
<output>70</output>

<gadget id="calculator">700 + 70</gadget>
<output>770</output>

<result>D</result>
boy sells a book for rs. 630 he gets a loss of 10 %, to gain 10 %, what should be the sp?
add(divide(630, subtract(const_1, divide(10, const_100))), multiply(divide(630, subtract(const_1, divide(10, const_100))), divide(10, const_100)))
"cost price = 630 / 90 x 100 = 700 to gain 10 % = 700 x 10 / 100 = 70 sp = cp + gain = 700 + 70 = 770 answer : d"