I have a problem and I don't know how I solve it. Can anyone help me?

Question

Question: to find the height of a fire tower, Lisa places a mirror on the ground 40 ft. from the base of the tower. Lisa's eye are 51/2 above the ground. When Lisa stands 4 ft. from the mirror, she can see the top of the tower in the mirror. How tall is the fire tower?

Answer 1

H / 40 = 5.5/ 4

H = 40*5.5/4 )

H = 10*5.5 = 55 ft

So Height of Tower / Height level of Eye = Distance of mirror from base of tower/ Distance of Lisa from mirror(Ratio proportion ) Angle being equal on both sides