13. (a) A man bought two books for Rs 1040. He sold one at a loss of 15% and other at a profit of 36% then he found that each book was sold for the same price. Find the cost price of each book.
(b) Shastika bought two watches for R's

Let the price of one book be Rs. x

price of next book is = 1040 - X

C.P of 1st book is Rs. x

Loss = 15%

S.P of 1st book = 85x / 100

C.P of 2nd book = 1040 - X

Profit = 36%

S.P of 2nd book = (1040 - x × 136)/100

(85x)/ 100 - (1040 - x × 136) / 100

85 x= 1040 x 136 - 136 x

85 x + 136 x= 1040 × 136

221 x = 1040 x 136

X = (1040 x 136) / 221

X = 640

So, Cost price for 1st book is 640 Rs. and 2nd book is 1040 - 640 = 400 Rs.

answer: 12

step-by-step explanation:

is it 35

step-by-step explanation: