P=2(l)+2(w)
90=2(4w-5)+2(w)
90= (8w-10)+2w
90=10w-10
10+90=10w-10+10
100=10w
w=10
90=2(4[10]-5)+2(10)
90=2(40-5)+2(10)
90=2(35)+20
90=70+20
90=90
The area of any trapezoid is
Area = (1/2) x (height) x (one base + the other base) .
Take that formula and write in the numbers you know:
(24 m²) = (1/2) x (height) x (5m + 7m)
(24 m²) = (6m) x (height)
Divide each side by 6m :
Height = (24 m² / 6m)
= 4 m .
You would plug in 6 where the x is so it would be -4 times 2 plus 5(6)
