Answer
$\$55,526.45$
Work Step by Step
Our salary, growing annually, can be considered as an investment. We know that the future value of it can be calculated as:
$FV=PV\times (1+r)^{t}$
Here, the present value, the starting salary is the question.
The future value is the salary we want to achieve, $FV=\$ 100,000$
The annual rate is $r=4\%$
The number of periods is $15$
Therefore the future value is:
$FV=PV\times (1+r)^{t}$
$PV=\frac{FV}{(1+r)^t}=\frac{100,000}{1,04^{15}}\approx 55,526.45$
