If Bill can buy 3 pairs of jeans and 2 shirts for $69 or 2 pairs of jeans and 3 shirts for $81, how much does one shirt cost?  Pick one
A) $10 B) $12 C) $13.20 D) $21 E) $16.80
3J + 2S = 69   2J + 3S = 81   ----------------   5J + 5S = 150 ----(divide by 5)---&gt; J + S = 30   3J + 2S = J + 2(J + S) = J + 60 = 69 ---&gt; J = 9   3*9 + 2S = 69   27 + 2S = 69   2S = 42   S = 21   Answer: $21
<result>D</result>
If Bill can buy 3 pairs of jeans and 2 shirts for $69 or 2 pairs of jeans and 3 shirts for $81, how much does one shirt cost?