Han is using 3 cups of water and will use 1 1/5 cups of cornmeal, which is right, because it's under the ratio 5:2. Basically, the number of cups of water is 2.5 times the number of cups of corn meal, because the given ratio is 5/2=2.5. If you multiply 1 1/5 x 2.5 = 3. So, Han is right.

On the other hand, Tyler is using 3 cups of cornmeal and he thinks will need 7 1/2 cups of water, which is also true, because the cups of water must be 2.5 times the cups of cornmeal, and 3 x 2.5 = 7.5 = 7 1/2.