Rex is making window cleaner by mixing vinegar and water. The ratio table below shows how much of each ingredient to mix together.
WINDOW CLEANER
Cups of
Vinegar
Cups of
Water
1
3
2.
6
3
9
If Rex uses 7 cups of vinegar, how many cups of water does he need to add?

21 cups of water

Step-by-step explanation:

(Left is vinegar, right is water)

1:3

2:6

3:9

4:12

5:15

6:18

7:21

21

Step-by-step explanation:

In the chart, the left side increases by one, and the right side increases by 3. So the left side multiplied by 3 will give you the right side. 7 x 3 = 21, so he will need 21 cups of water.