Answer:
The baker uses 15 cups of cereal for 10 cups of marshmallows
Explanation:
The proportion 6:4 has to stay true in the answer, so both numbers have to be multiplied by the same number
6 x 2.5 = 15
4 x 2.5 = 15
both numbers were multiplied by the same number in this answer and it is the only answer that stays true to the ratio