$110,000
Marketers = 50000
Engineers = 80000
Managers = X
Average = sum/number of values
Sum = 50000 + 80000 + X
Number of values = 3
80000 = (50000 + 80000 + X)/3
Solve to find X
Multiply both sides by 3
240000 = 50000 + 80000 + X
Get X on its own by subtracting the salaries.
240000 - 80000 - 50000 = X = 110000
