IKMC 2027 - Grades 7-8 - Self-study SET 13 - Thematic Batch 3 Question 29

The asteroid Cere is inhabited by two alien species, Zid and Zod. Together they have 165 legs. Each Zid has 5 legs and each Zod has 17. How many aliens are there?

Editorial interpretation: Both species mentioned as inhabitants are present, so each species count is positive.