Question 980579
-Adrian and Betty have been teaching for a total of 36 years.

            -Charlie and Betty have been teaching for a total of 22 years.

            -Charlie and Adrian have been teaching for a total of 28 years.

How long has each been teaching?
==================
a + b + 0 = 36
0 + b + c = 22
a + 0 + c = 28
---------------
---
a + b + 0 = 36
0 + b + c = 22
------------------- Subtract
a - c = 14
a + c = 28 3rd equation
---------------------------- Add
2a = 42
a = 21
Can you do the rest?