Step-by-step explanation:
Length is three times 5 less than width so,
Let width be =x
And let lenght be = x-3*5
Perimeter=2*(l+b)
2*(x-3*5+x)=150
2*(x-15+x)=150
(expand)
2x-30+2x=150
4x=150+30
4x=180
x=180/4
x=45
Lenght=x-3*5
45-15=30
Checking,
2(45+30)
2*75=150
Hope it helps
