Plz help with the correct answer please

Rose would be saving 50 dollars after 10 months. So you know that Rose got $10 in 0 months and $14 in the next month and again.This means that every month it adds up to another $4. If you want to find the total or 10 months keep on add 5 4 times which is 20. Then add 30 from the 0-5 months and which gives you $50. So Rose would be saving up 50 bucks in 10 months.

Final Result: 50

the formula of a midpoint between a abd b:

i believe the answer is y=0.25x+-3