Answer:
3 and 3/4 cups of cornstarch
Explanation:
5/8 cornstarch = 1/6 cup of water
1/6 x 6 = 1 cup of water so we multiply the 5/8 of cornstarch by 6 on the other side, because what you do to one side you must do to the other.
5/8 * 6/1 = 15/4 or 3 and 3/4 cups of cornstarch is needed (this is also 3.75 in decimals)