In an amphitheater, there are 20 seats in the front row, 23 seats in the second row, 26 seats in the third row, and so on, in an arithmetic sequenc A) Write an explicit formula to find an. the number of seats in the nº row. B) The last row in the amphitheater has 83 seats in it. How many rows a seats are there?

C) Write an expression using sigma notation that represents the total number of seats in the amphitheater.

D) Evaluate this expression. How many total seats are there?