Answer:
Sam is 10 years old.
Step-by-step explanation:
40/2=20-10=10
Since he is half the age of his aunt we can divide his aunts age(40) by 2(to get half her age). Then we have 20, but it says he is 10 years younger than half her age. So we subtact half Sam's aunts age(20) by 10, and end up with 10.
Hope this helps!!