The perimeter of a rectangle is 80 feet. Find the dimensions if the length is 5 feet longer than 4 times the width. Then find the area of the rectangle. I know that P=2(l+w) 11/12/2013 | Conny from Elk Point, SD | 2 Answers | 0 Votes Mark favorite Subscribe Comment
Hi Conny; L=4W+5 80=2L+2W 80=2(4W+5)+2W 80=8W+10+2W Let's combine like terms... 80=10W+10 Let's subtract 10 from both sides as we proceed to isolate x... 80-10=10W+10-10 70=10W Let's divide both sides by 10... 70/10=(10W)/10 7=W L=4W+5 L=4(7)+5 L=28+5 L=33 Let's check our work... 2W+2L=80 [2(7)]+[2(33)]=80 14+66=80 80=80 11/12/2013 | Vivian L. Comment
l = 4w + 5 P = 2[(4w + 5) + w] = 80 (4w + 5) + w = 80 / 2 5w + 5 = 40 5w = 40 - 5 w = 35 / 5 = 7 feet l = 4 * 7 + 5 = 33 feet ------- Verify the answer: 2(33 + 7) = 80 2 * 40 = 80 80 = 80 11/12/2013 | Nataliya D. Comment