Answer:
1.5
Explanation:
The constant of proportionality is simply the ratio between two items. In this case, we want the ratio of pancake mix to milk.
We have 9 cups of pancake milk and 6 cups of milk, so our ratio will be:
9 cups : 6 cups ⇒ 3 cups : 2 cups
3:2 can be written as the fraction 3/2, which can be simplified to the decimal 1.5.
Hope this helps!