Answer:
Step-by-step explanation:
If Tim is 3 years older and five years ago, the sum of their ages is nineteen you need to find two addends that are 3 greater than each other.
So, 11+8 = 19
Five years ago Tim was 11 and his sister was 8.
add 5 to 11 = 16
Tim is 16 now
I don't know the equation though sorry
Hope this helps you :)