What is this man's total earning for a 8-year period?

Question

A man gets a job with a salary of 38900 dollars a year. He is promised a 2510 dollars raise each subsequent year.

His total earning for a 8-year period is ______  dollars.

Answer 1

it's an arithmetic sequence

an=a1+d(an-1)

a8=38900+2510(7)=38900+17570

= $56,470 for 8th year

sn=n(a1+a8)/2

s8=8(56470)/2

=$225,880 =total for 8 years