In this case you can consider that the stick and its shadow, and also the telephone pole and its shadow are triangles. Furthermore, because their shadows are projected at the same time, you can consider tha both triangles are simmilar between them.
The first triangle (formed by the stick and its shadow) has its vertical side of 1 m and its horizontal side is of 1.5 m (the shadow). The second triangle (telephone pole and its shadow) has a horizontal side of 9 m and has an unknown vertical side.
Due to both triangles are simmilar you have that the ratio between the vertical and horizontal side is equal for both sides, that is:
1/1.5 = x/9
Numerators are the vertical sides and denominators are the horizontal sides. You multiply by 9 both sides of the previous equation in order to cancel the denominator 9 of the right side:
9(1/1.5) = 9(x/9)
9/1.5 = x
6 = x
Hence, the vertical side of the second triangle is x = 6. This vetical side corresponds to the tall of the telephone pole, that is, the tall is of 6 meters.