I'm guessing the sum is supposed to be

Split the summand into partial fractions:


If
, then

If
, then

This means

Consider the
th partial sum of the series:

The sum telescopes so that

and as
, the second term vanishes and leaves us with

Please, share the goal of the problem. If Carrie works 40 hours per week and spends 15% of her time at the register, how much time does she NOT spend at the register?
Subtract 15% from 100%; the result is 85%. Now find 85% of 40 hours:
0.85(40 hours) = 34 hours.
Please note that I invented part of this problem. Next time, share all of the info so that someone can help you solve YOUR particular problem.
This is a question that involves multiplication. If 1 baseball weighs 5 ounces, and you're trying to find out how many 6 weigh, multiply 5x6. The answer is 30. Hope this helps.