Question

A manager purchased a total of 21 coffee mugs and key chains. each coffee mug cost $8.50, and each key chain cost $2.75 . if manager spent total of $132.50, how many coffee mugs did the manager purchase please help solve this I put a answer just not positive it's right

Answer 1

$x + y = 21 \\ 8.5x + 2.75y = 132.5$
$8.5x + 2.75( - x + 21) = 132.5$
$8.5x - 2.75x + 57.75 = 132.5$
$5.75x + 57.75 = 132.5$
$5.75x = 74.75$
$x = 13$
13 coffee mugs