Brown Delivery Company delivers its standard crates using a fleet of vans and trucks. A van can hold up to 20 standard crates, and a truck can hold up to 35 standard crates. If Brown Delivery Company needs to deliver exactly 270 standard

crates at one time using 12 vehicles, which system of linear equations could be used to determine the number of vans, x,

and the number of trucks, y, needed for this delivery?

x + y = 12

20x + 35y = 270

x + y = 270

20x + 35y = 12

x + y = 12

35x + 20y = 270

x+y = 270

35x + 20y = 12