Let’s denote Sally’s age as x. According to the information given, Tim is 10 years older than Sally, so Tim’s age would be x + 10.
The total of their ages is 100 years, which means the equation x + (x + 10) = 100 is true.
Simplifying the equation, we have 2x + 10 = 100.
Subtracting 10 from both sides of the equation, we get 2x = 90.
Dividing both sides by 2, we find x = 45.
Therefore, Sally is 45 years old.
I hope you find this helpful.