 
 <prompt> Pablo nweta 4 ọnụahịa nke mmepe ụlọ. Ọnaghị ekpe nwere 5 ọnụahịa. Ekpe abụọ nwere ọnụahịa 2 nke ọnụ. Ekpe atọ nwere ọnụahịa 5 nke ekpe abụọ, ma ọ bụghị ekpe dị n'ime nke abụọ. Kedu ọnụahịa mmepe ụlọ Pablo jiri niile? <response>: The number of blocks in the second stack is 5 + 2 = 7.
The number of blocks in the third stack is 7 − 5 = 2.
The number of blocks in the last stack is 2 + 5 = 7.
Pablo used 5 + 7 + 2 + 7 = 21 toy blocks in all.

The answer will be 21. 