Fractional Increase

[Chikis]

Father reduced the
quantity of food
bought for the
family by 10%
when he found
that the cost of
living had increased
by 15%. Thus the
fractional increase
in the family food
bill now is what?

I don't know how
those things relate
to one another.


The quantity of
food bought for
the family is not
given. In fact, I
don't know how
those things relate
to one another.

Where and how do
I start from?

[Jonasmathwork]

Solution: You can start with assuming the fractional increase in new bill =x
given that father reduce in food by 10%=(1-10/100)
and cost of food increase by 15%=(1+15/100)

there for the fractional increase in new bill x=[(1-10/100)(1+15/100)]-1
x=35/1000
x=3.5%

there for the fraction increase in new bill by 3.5%.

Hope you got your answer.