Huilan is 15 years younger than Thomas. The sum of their ages is 65. What is Thomas's age?

Thomas's age: 40

Step-by-step explanation:

We have:

Thomas's age - Huilan's age = 15 (1)

Thomas's age + Huilan's age = 65 (2)

Add 1 and 2 we have :

2T = 65+15

<=>2T = 80

So Thomas's age is 40.

P/s: T is Thomas's age