Question 331762
let length be x mi
width = x-90 mi
..
perimeter = 2*(L+W)
1280 = 2*(x+x-90)
1280=2*(2x-90)
1280/2 = 2x-90
640 = 2x-90
640+90=2x
730=2x
x= 365 miles the length
..
width = 365 -90 = 275 miles
CHECK
275*2+365*2=550+730=1280