Answer:
After 31 months, Desmond first have enough money to purchase a used car.
Explanation:
Since we have given that
Saving per month for a used car = $25
Each month he is able to save = $5 more than the previous month
If we have $3000 to purchase a used car.
So, we need to find the number of months Desmond to have enough money.
Our sequence will be
25,30,35,..............3000
So, it becomes,
Months can't be negative, So,
n = 31 months.
Hence, After 31 months, Desmond first have enough money to purchase a used car.