Kim and courtney share a 16-ounce of box of cereal. by the end of the week, kim has eaten 3/8 of the box, and courtney has eaten 1/4 of the box of cereal. what fraction of the box is left?

No. of ounces Kim ate = 3/8 * 16 = 6 ounces
No. of ounces Courtney ate = 1/4 * 16 = 4 ounces
No. of ounces left = Total amt. of cereals - Kim's share - Courtney's share
                          = 16 - 6 - 4 =6 ounces
Fraction of left over cereal = 6/16 = 3/8