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?
The number of blocks in the second stack is 5 + 2 = 
<gadget id="calculator">5+2</gadget>
<output>7</output>
7.
The number of blocks in the third stack is 7 - 5 = 2.
The number of blocks in the last stack is 2 + 5 = 
<gadget id="calculator">2+5</gadget>
<output>7</output>
7.
Pablo used 5 + 7 + 2 + 7 = 
<gadget id="calculator">5+7+2+7</gadget>
<output>21</output>
21 toy blocks in all.

<result>21</result>