Can someone explain me how to do this? No answers, just explanation how to solve. Click on the picture to see the question.

Answer:
800 cm
Step-by-step explanation:
x = height of lamp post
set up a proportion:
90/160 = 450/x
cross-multiply:
90x = 72000
x = 800
Answer:
Since you did not want the answer the things you need to solve this question are below.
Step-by-step explanation:
In order to solve this, you will need to read about the scale factor. Here is a picture telling about it briefly.