Researchers acknowledge the importance of computational thinking for all, not only computer scientists. Strong links between computational thinking and mathematics led to the integration of computational thinking into mathematics curricula in many countries around the world. This ongoing research aims therefore to deepen our understanding of what computational thinking is and what the relations between mathematics and computational thinking are when secondary school students solve mathematics problems. This contribution proposes an a priori analysis of a task that was experimented with Grade 8 students, to highlight the interplay between mathematical and computational thinking mobilized in the solving process.