 
<translate> Ọ bụrụ na e nwere azụ iri asatọ n'ozuzu, mgbe ahụ e nwere azụ iri asatọ / 2 = azụ iri anọ na-acha anụnụ anụnụ. Azụ oroma na-erughị 15 karịa nke na-acha anụnụ anụnụ, yabụ ọ bụ azụ 40 - azụ 15 = azụ 25. Olaf nwere azụ iri asatọ - azụ iri abụọ na ise - azụ iri anọ = azụ iri na ise. N'ihi ya, azịza ya bụ 15. <eng> If there are 80 fish in total, then there are 80 fish / 2 = 40 blue fish. The orange fish count is 15 less than blue, so it's 40 fish - 15 fish = 25 fish. Olaf has then 80 fish - 25 fish - 40 fish = 15 green fish.
Thus, the answer is 15. 