what is the % change in the area of a rectangle when its length increases by 30 % and its width decreases by 30 % ?
"( 13 / 10 ) * ( 7 / 10 ) = 91 / 100 of original area 91 / 100 is a 9 % decrease from 100 / 100 - > d"
subtract(const_100, divide(multiply(add(const_100, 30), subtract(const_100, 30)), const_100))