A stack of 6 bricks is 2 feet high. How high is a stack of 20 bricks?

60.

The question gives you the fact that 6 bricks is 2 feet high.

What do you do to get from 2 to 20?

You multiply by 10.

Since you multiplied one thing by 10, you must do it to the other side so it remains balanced.

2 ft x 10ft = 20ft

6 bricks x 10 bricks = 60 bricks