The perimeter of a rectangle is 100 yd. if its width is four times its length, what is the area?

Length = l

Width = w

Perimeter = p = 100

Perimeter of rectangle = 2(l+w)

100 = 2 (4w + w)

100 = 2(5w)

100 = 10w

100/10 = w

10 = w

w =  10

Area of rectangle = length * width

a = l*w

a = 4w*w

a = 4w^2(1)

Put the value of w in (1)

a = 4(10)^2

a= 4(100)

a = 400 yd^2

answer: c

because if you look at the chart you can see a pattern and compare it to the question he simplify out your

but i think the formula is f(x)=6x