Pre Algebra
posted by Izabel on .
The ratio of the length of a rectangular field to its width is 10:7 if the width of the field is 70 meters find the perimeter of the field.

length = L
width = w
Ratio = L:w = 10:7 = L:70
10:7 = L:70
10/7 = L/70
cross multiply
700 = 7L
L = 100
L = 100, w = 70
P = 2w + 2L
P = ? 
let the length be 10x
let the width be 7x , ( notice the ratio 10x : 7x = 10:7 )
given : 7x = 70
x = 10
Perimeter = 2(10x+7x) = 34x = 340
check:
length =100
width =70
perilmeter = 100+100+70+70 = 340