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.

25.2

step-by-step explanation:

2+4x6-8/10= 25.2

the total estimated nappy use.=10,500,000

step-by-step explanation:

given that on an average the average baby uses 3528 napkins.

in a particular year 2014, the number of births were 299697 in new south wales.

rounding off the number of births to the nearest hundred thousand we have

no of birtsh = 300000

also rounding off the average usage to nearst thousand we get

average use of a baby = 3500

hence total number of nappy estimated to be used = 3500x300000

= 10,500,000

answer is 10,500,000 nappies