7 months because after the 100 dollars u add u 25 7 times to get 275
C=hx+sx+d
It's basically a spinoff of the y=mx+b formula except there are two x's in case you don't know exactly how many to buy or else you'd literally just add them all together. I hope this helps and gives you a better idea on how to solve it.
Answer:
13+8(n-1) is the pattern of how this series goes on where n is the number of entities being added.
Write n at the top of sigma notation which is 5 here. And write the pattern infront of sigma notation which is 13+8(n-1)here.
Tuesday at 2pm because 2 goes in 24 evenly. so whenever the 24 hours is up, she'll check it.