Maria bought 7 boxes. A week later half of all her boxes were destroyed in a fire. There are now onl

Maria bought 7 boxes. A week later half of all her boxes were destroyed in a fire. There are now only 22 boxes left. With how many did she start?

Let x be the starting box number. We have:
(x + 7)/2 = 22

Cross multiply
x + 7 = 44

Subtract 7 from each side
x = 37