we know that
The perimeter of rectangle is equal to
P=2(L+W)
In this problem we have that
must be less than 150in., and the width is 28in
so
P=2(L+28)
2(L+28) < 150
divide by 2 both sides
L+28 < 150/2
L+28 < 75
solve for L (L is the height of the frame)
simplify
L+28 < 75
L < 75-28
L < 47 in
therefore
The height must be greater than 47 inches
