Question

charlie paid $660 for 6 shirts and 4 belts. one shirt costs three times as much as one belt. if charlie bought 5 such shirts and 2 such shirts, how much would he have to pay?

Answer 1

let shirts is x and belt y
$6x + 4y = 660$
$x = 3y$
$18y + 4y = 660 \\ 22y = 660 \\ y = 30 \\ x = 90$
therfore
$5(90) + 2(30) = 510$