18. 3 cups of water, convert it to pints:
[tex]\begin{gathered} 1pint=2cups \\ \\ 3cups*\frac{1pint}{2cups}=1.5cups \end{gathered}[/tex]
To make a double recipe she needs to use 2 pints of water.
Then, the 3 cups of water Cheryl has measured are not enought for a double recipe.
19. The recipe uses 1/2 cup of cornstarch
To make 15 time the recipe the amount of cornstarch is:
[tex]15*\frac{1}{2}cup=7.5cups[/tex]
Convert the 7.5cups to tablespoons:
[tex]7.5cups*\frac{16tbsp}{1cup}=120tbsp[/tex]Then, to make 15 times the recipe Cheryl needs to use 120 tablespoons of cornstarch
