A company decides to set aside $100,000 for development of a new product.
It estimates that development will cost $955 the first week and that expenses will increase by $65 each week.

After 25 weeks, how much of the development budget will be left?

Question

A company decides to set aside $100,000 for development of a new product. 
It estimates that development will cost $955 the first week and that expenses will increase by $65 each week. 

After 25 weeks, how much of the development budget will be left?

tkhunny · Answer

Week 1 955
Week 2 955 + 65
Week 3 955 + 65*2
Week 4 955 + 65*3

That looks like an Arithmetic Sequence.  I wonder if there is a way to add up some finite number of those terms?