62 decreased by twice gail’s height let g represent gail’s height

62 - 2g

Explanation:
Before we begin, note the following:
a decreased by b means that we will subtract b from a, In other words, the expression would be a - b

Now, for our problem:
We have "g" is Gail's height.

The given information is as follows:
i. twice Gail's height means that we will multiply the height by 2. This will give us 2g
ii. 62 decreased by 2g means that we will subtract 2g from 62.

Based on the above, the expression would be:
62 - 2g

Hope this helps :)

The answer would be 7 cages