Answer:
Let j = number of shirts Jeff bought and s = the number of shirts Stephen bought.
a.) s + j = 15
b.) 2j - 3 = s
c.) Plug 2j -3 into the equation from question a.
2j -3 + j = 15
3j -3 = 15
3j = 18
j = 6
2j - 3 = s when j = 6
2(6) - 3 = s
s = 9
Jeff bought 6 shirts; Stephen bought 9 shirts.
d.) Jeff cost = 8.99(6) = $53.94
Stephen cost = 8.99(9) = $80.91