Answer
$3x+3y = 195$
$4x+7y = 390$
$x = 25$ minutes (small centerpiece)
$y = 40$ minutes (large centerpiece)
Work Step by Step
$3x+3y = 195$
$4x+7y = 380$
x = small, y = large
$3x+3y = 195$
$-4*(3x+3y = 195)$
$-12x-12y = -780$
$4x+7y = 380$
$3*(4x+7y = 380)$
$12x + 21y = 1140$
$-12x-12y +12x + 21y= 1140-780$
$9y = 360$
$9y/9 =360/9$
$y = 40$
$3x+3y = 195$
$3x+3*40 = 195$
$3x+120 = 195$
$3x+120-120 = 195-120$
$3x = 73$
$3x/3 = 75/3$
$x = 25$
