If Greg buys 3 shirts, 6 trousers and 4 ties, the total cost is $80. If Greg buys 7 shirts, 2 trousers and 4 ties, the total cost is $80. How much will it cost him to buy 5 trousers, 4 shirts and 4 ties?
Options:
A) $60
B) $64
C) $80
D) $96
E) Cannot be determined
Solution: 3x+6y+4z=80 7x+2y+4z=80   adding both the equations= 10x+8y+8z=160   5x+4y+4z=80   ans $80
<result>C</result>
If Greg buys 3 shirts, 6 trousers and 4 ties, the total cost is $80. If Greg buys 7 shirts, 2 trousers and 4 ties, the total cost is $80. How much will it cost him to buy 5 trousers, 4 shirts and 4 ties?