A local high school held a two-day fundraiser selling lunches. The equations shown represent the amount of money the school collected during the two days.
{12x + 4y = 15232x + 12y = 42012x + 4y = 15232x + 12y = 420
In the equations, xx represents the cost of a chicken lunch and yy represents the cost of a vegetarian lunch. Which is the cost of the vegetarian lunch?
$9
$11
$13
$21