SOLUTION: The perimeter of a rectangle is 84 feet. The ratio of the width to the length is 2:5. Find the length and the width. How do i set up this ratio? 2 is to 5 as x is to 84? I don't k

Algebra ->  Rectangles -> SOLUTION: The perimeter of a rectangle is 84 feet. The ratio of the width to the length is 2:5. Find the length and the width. How do i set up this ratio? 2 is to 5 as x is to 84? I don't k      Log On


   

Question 831773: The perimeter of a rectangle is 84 feet. The ratio of the width to the length is
2:5. Find the length and the width. How do i set up this ratio? 2 is to 5 as x is to 84? I don't know how to set the problem up!
Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
we are given width (w)/length (l) = 2/5, now cross multiply the fraction
5*w = 2*l NOTE that * means multiply
solve for w = (2*l) / 5
we also know that
2*w + 2*l = 84
now substitute for w
2 *(2*l)/5 +2*l = 84
multiply both sides of = by 5
2*(2*l) +10*l = 420
14*l = 420
l = 30
substitute in perimeter equation
2*w + 2*30 = 84
divide both sides of = by 2
w +30 = 42
w = 12
ratio of w/l = 12/30 = 2/5
our answer checks :-)
width is 12 feet and length is 30 feet