Can you help me on question 7?! :)

Sam is using the correct amount.

Step-by-step explanation:

A ratio is simply a way of saying a this amount of this for this amount of that.

When a ratio is 3:1 it means for every 3 parts of one thing, you have 1 part of another.

If you look at Alyssa she's using 6 parts of water for 4 parts cornstart. If you reduce this down by dividing by 2 it's 3 parts water for 2 parts water.

So in Sam's case. He's using 15 parts water for every 5 parts of cornstatch. Thus if you reduce by dividing both parts by 5 you get, 3 parts water for 1 part cornstartch.

Thus Sam's ratio is 3:1

10 is A

11 is D

12 is C

and 13 is B