Question

Jim had a box full of baseball cards on Monday he gave 1/3 of them to John on Tuesday he gave 10 of them to Jeff finally on Wednesday Jim gave half of the remaining cards to Joe if 15 baseball cards are left in the box how many did it originally contain

Answer 1

120 baseball cards

Explanation:

15 × 2 = 30

30 + 10 = 40

40 ÷ 1/3 = 40 × 3/1 = 120

Therefore there were 120 cards in the back

I just did the inverse of each process starting from the last step and ending at the first