what is the % change in the area of a rectangle when its length increases by 60 % and its width decreases by 60 % ?
"( 16 / 10 ) * ( 4 / 10 ) = 64 / 100 of original area 64 / 100 is a 36 % decrease from 100 / 100 - > c"
subtract(const_100, divide(multiply(add(const_100, 60), subtract(const_100, 60)), const_100))