Question

Mary sold half of her comic books and then bought 8 more. she now has 18. how many did she begin with?

Answer 1

She had 20 books

Explanation:

If she bought 8 more and in total she have 18 before she buy those 8 books she had 10 so `10*2 = 20` because she sold half of her books that means she had double the amount of 10.

Answer 2

20

Explanation:

Work backwards from the final count.

Final count `->18`

This was after adding eight more `18-8=10`

This was after selling half the original amount

original amount `->2xx10=20`