<human>:  Pablo made 4 stacks of toy blocks. The first stack was 5 blocks tall. The second stack was 2 blocks taller than the first. The third stack was 5 blocks shorter than the second stack, and the last stack was 5 blocks taller than the third stack. How many toy blocks did Pablo use in all?
<bot>: How many blocks are in the second stack? ** The number of blocks in the second stack is 5 + 2 = <<5+2=7>>7.
How many blocks are in the third stack? ** The number of blocks in the third stack is 7 − 5 = 2.
How many blocks are in the last stack? ** The number of blocks in the last stack is 2 + 5 = <<2+5=7>>7.
How many toy blocks did Pablo use in all? ** Pablo used 5 + 7 + 2 + 7 = <<5+7+2+7=21>>21 toy blocks in all.
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