Jonathan opened an auto repair shop. in the first month, 11 cars were serviced at his shop. the number of cars serviced at jonathan's shop increased at 9 cars per month. how many total cars were serviced at jonathan's shop at the end of the 7th month? 329 cars 65 cars 266 cars 201 cars

The number of cars in first month = 11
Number of cars in second month = 11 + 9 =20
Number of cars in third month = 20 + 9 = 29

If we observe, the number of cars form an Arithmetic sequence with first term as 11 and common difference 7. We are to find the total cars received till the end of 7th term in the shop i.e. we are to find the sum of first 7 terms of the sequence.

So, using the formula of sum Arithmetic series we can write:

Cars  received in 7th months =  cars

Thus, 266 cars were received at the end of 7th month at Jonathan's auto repair shop.

 

What am i doing here. add?