4.75/1.25 = 3.8

1.60 x 3.8 = 6.08

The tree would be 6.08 meters tall.

6/1.25 = 4.8

1.60 x 4.8 = 7.68

The tree would be 7.68 meters tall.

BC/FC = 1.8

AC/EC = 1.8

x/EF = 1.8

5.4 x 1.8 = 9.72

x = 9.72

15.9/8.7  =  x/5.4

15.9 x 5.4/8.7 = x

x = 9.9