Question

a number is first increased by 15% and then reduced by 15%. by what percentage does the number change?

Answer 1

let the no. be x 
15% + x = 15/100 + x
= 3/20 + x
3/20 + x - 15%
= 3/20 + x - 3/20
so both 3/20 was subtracted leaving nothing.
=x
so by 0% or none percentage the no. change.

Hope it helps!!!

Answer 2

(15/10)^2=2.25% decrease
this is the formula ... if same no 1st increase then decrease then always there is decrease
please mark it as a brainliest answer