Let L represent length of rectangle
Let W represent width of rectangle
L=4W
2L+2W=70
Substitute 4W for L
2(4W)+2W=70
8W+2W=70
10W=70
Divide both sides by 10
W=7
Use equation from beginning
L=4(7)
L=28
Width is 7 ft, length is 28 ft
Check work
2(28)+2(7)=70
56+14=70
70=70