If the length of the base of a rectangle is increased by 30 percent but the length of the altitude is decreased by 40 percent, by what percentage is the area changed?

i think a picture with help

the simplified form is

step-by-step explanation:

we want to simplify the expression,

let us change the middle bar to a normal division sign to obtain,

we multiply the first fraction by the reciprocal of the second fraction to obtain,

we factor to obtain,

we cancel the common factors to get,

we simplify to get,

the correct answer is b