let length = x
width is 7 feet less than length
width = x-7
area = length *width
area = x(x-7)
170=x²-7x
x²-7x-170=0
x²-17x+10x-170=0
x(x-17)+10(x-17)=0
(x-17)(x+10)=0
x=17 or x=-10
since length cannot be negative so x=17
and width =x-7 =17-7=10
length =17 feet and width =10 feet
