Colise has 2 vases of flowers that each hold 10 red and 5 yellow roses. Michelle has the same total number of roses but in 3 vases. Each vase has 6 red roses.

How many yellow roses is in each of Michelle's vase?

Colise : 2 vases ... each hold 10 red and 5 yellow ... 2 (15) = 30 roses total.

Michele also has 30 roses. She has 3 vases ... each vase has 6 red roses ... 6 * 3 = 18 red roses. That leaves 30 - 18 = 12 yellow roses. And I am assuming that each vase has the same number of roses ... in that case, 12/3 = 4 yellow roses per vase