Question

irvin sold a book at a profit of 12%. if Irvin had sold it for rs. 18 more, then 18% would have been gained. find the cost price.

Answer 1

Let the CP of the book be ₹ x .Then S.P at a gain of 12%

S.P =( (100+12)/100) × x

[ S.P = ((100+gain%)/100)×C.P]

S.P= 112x/100...............(1)

When S.P is increased by ₹ 18 ,gain is 18%

S.P +18 = ( (100+18)/100) × x

S.P+18 = 118x /100

Put the value of S.P obtained from 1 &2

112x/100+18= 118x/100

18= 118x/100-112x/100

18 = 6x/100

18×100 = 6x

x= (18×100)/6

x= 3×100

x= ₹300

Hence,the C.P of a book = ₹300

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