Answer:
Thomas is 20 years old.
Explanation:
Let's use algebra to solve this problem.
Algebra is a branch of mathematics that deals with the manipulation of symbols, called variables, and the rules for operating on them.
For the Question:
Let x represent Thomas's age and y represents Huilan's age.
We have two pieces of information:
Huilan is 5 years younger than Thomas:
This can be expressed as:

The sum of their ages is 35:
This can be expressed as:

Now, we can substitute the value of H from the first equation into the second equation:

Simplify the equation:

Add 5 to both sides:


Divide by 2 on both sides:


So, Thomas is 20 years old.