Question

So I've gotten 3 different answers on my question

"Mark is 15 years younger than Ashley. The sum if their ages is 55. Write a system of equations to determine Mark (M) age and Ashley (A) age"
and I just want another opinion on how to write both equation and how to solve them please!
The answer I got most recently was "A-M=55 and A-15=55" which sounds right but I don't know how I'd solve for Ashley or Marks age

Answer 1

the sum of their ages is 55. that means that
A + M = 55
Mark is 15 years younger/Ashley is 15 years older. that means that
M + 15 = A and, conversely, A - 15 = M
remove 15 from the 55 to get 40, divide that by 2 (for the two people) and get 20.
M = 20 and A = 20 + 15 = 35

you can plug these in to check: 20 + 35 = 55, and 35 is 15 more than 20