 
 <prompt> ```Alex nwere ihe nkiri ọcha ọ bụla. Joe nwere ihe nkiri ọcha 3 nweta nke Alex. Ben nwere ihe nkiri ọcha 8 nweta nke Joe. Ọ bụrụ na Ben nwere ihe nkiri ọcha 15, onye nkiri ọcha Alex nwere ihe nkiri ọcha ozi nke ihe gbasara?``` <response>: ```Joe nwere ntụgharị 15-8=7 ntụgharị ọzọ.
Alex nwere ntụgharị 7-3=4 ntụgharị ọzọ.

Ntụgharị akpọ: 4.``` 