Answer: 3/4 cups per cake.
Step-by-step explanation:
He needs 3 cups for 4 cakes.
Then, if you want to know the amount that he needs for each cake, you need to see the quotient between the number of cups and the number of cakes:
S = 3cups/4 cakes = (3/4) cups per cake.
In the number line, 3/4 will be:
0--I--I--(here)--1--I--I--I--2