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@greenestamps correctly noticed that this problem formulation admits SEVERAL different interpretations.
I came with my own interpretation and with my own solution.
After the 1st year, the salary is 1.12 of the original salary.
After the 2nd year, the salary is 1.16*1.12 of the original salary.
After the 3rd year, the salary is 1.19*1.16*1.12 of the original salary.
After the 4th year, the salary is 1.25*1.19*1.16*1.12 of the original salary.
So, after 4 years, the salary is 1.25*1.19*1.16*1.12 = 1.93256 of the original salary.
They want you to find an EQUIVALENT annual growth coefficient that provides this calculated increase of salary in four years.
For it, you should solve this equation
= 1.93256.
It is easy to do:
1 + r = = 1.179 (rounded).
It gives then average annual percentage increase r = 1.179 - 1 = 0.179, or 17.9%. ANSWER
Solved, with my interpretation N 3.