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

Question

Answer 1

38,900 with annual raise of 2,510 for 8 years

it's an arithemtic series

an = a1 + d(n-1) where d= common difference = 2510, n=8, a1 = 38,900

a8 = 38900+2510(7)

a8 = 38900 + 17,570

s8 = (8/2)(38900 + 46470)

= 4(85370)

= $421,480= total earnings for 8 years

before taxes

s8 = $4