#4(a)
row-seat: 3- 13, 4-15, 5-17, 6-19, 7-21
(b)
the equation works for row 1 but not for any of the rows after this
Ex: Row 2, S=7(2)+2, this would equal 14 but there isn't 14 seats in row #2
(c)
S=2(1)+7, there is 9 seats in row 1
2(2)+7=11, there is 11 seats in row 2
2(3)+7= 13, there is 13 seats in row 3
(d)
2(15)+7=37
2*15=30, 30+7=37
(e)
91=2(r)+7
91-7=2(r)+7-7
84=2(r)
84/2=2(r)/2
42=r, the row with 91 seats is row 42