Answer:
Thomas is 45 years old
Step-by-step explanation:
We can start by setting up the problem as X(Thomas age) + Y(Huilans age) =83
X+Y=83
The problem gives us Huilan's age in terms of Thomas' so we would rewrite it as:
X+(X-7)=83
Now we solve for X:
X+X-7=83
-add 7 to both sides
X+X=90
-combine like terms
2X=90
-divide both sides by 2
X=45 (This is Thomas' age)