Alex can read 8 pages in 20 minutes. How long will it take him to read 20 pages?

20 / 8 = 4 * 5 / ( 4 * 2 ) = 5 / 2 = 2.5 min / page

2.5 * 20 = 50 min

OR

8 / 20 = 20 / x Multiply both sides by x

8 * x / 20 = 20 * x / x

8 x / 20 = 20 Multiply both sides by 20

8 x * 20 / 20 = 20 * 20

8 x = 400 Divide both sides by 8

8 x / 8 = 400 / 8

x = 50 min

To find out how long it will take Alex to read 20 pages, we can set up a proportion using the given information.

First, let's determine the rate at which Alex reads. We know that he can read 8 pages in 20 minutes. So, his reading rate is 8 pages per 20 minutes, which can be simplified to 2 pages per 5 minutes.

Now, we can set up a proportion. Let "x" represent the time it takes Alex to read 20 pages.

8 pages / 20 minutes = 20 pages / x minutes

To solve this proportion, we can cross-multiply:

8x = 20 * 20

Simplifying the right side:

8x = 400

Dividing both sides by 8:

x = 400 / 8

x = 50

Therefore, it will take Alex 50 minutes to read 20 pages.