Find a, for the arithmetic sequence with a? = 5,d = ?4, n=98.(a) -392(b) -387(c) -383(d) 393Determine the seating capacity of an auditorium with 30 rows of seats if there are 25 seats in the first row, 28 seats in the second row, 31 seats in the third row, and so on.(a) 1635(b) 1792(c) 2055(d) 3125