Erin made 4 stacks of wooden blocks. The first stack was 5 blocks tall. The second stack was 10 blocks taller than the first. The third stack was 13 blocks shorter than the second stack, and the last stack was 8 blocks taller than the third stack. How many blocks did Erin use in all?

Answer 1

first 5 blocks
second 15 blocks
third 2 blocks
fourth 10 blocks
I bet you can add 5+15 + 10 + 2

Answer 2

5 + 10 = 15

15 - 13 = 2

2 + 8 = 10

5 + 15 + 2 + 10 = ?