Choice C is the correct answer. Let $a$ be the number of adult tickets and $c$ be the number of child tickets.

Given: $a = 2$ and $8a + 5c = 41$

Step 1: Substitute $a = 2$: $8(2) + 5c = 41$$16 + 5c = 41$

** Step 2**: Solve for $c$: $5c = 25$$c = 5$

Solution: They bought 5 child tickets.

Verification: $8(2) + 5(5) = 16 + 25 = 41$ ✓

💡 Strategic Tip: When one value is given, substitute it immediately to simplify the problem.

Choice A is incorrect because$8(2) + 5(4) = 16 + 20 = 36 \ eq 41$.

Choice B is incorrect because$8(2) + 5(6) = 16 + 30 = 46 \ eq 41$.

Choice D is incorrect because$8(2) + 5(3) = 16 + 15 = 31 \ eq 41$.