System word problems.. does anyone understand this.

X = number of tickets sold in advance, and thus cheaper.

x + 206 = number of tickets sold at the door.

now, the ones sold at the door, are more expensive and is more than the early sold tickets, as you know is x + 206.

now, if the early ones cost each one 6 bucks, then the cost for all of them is 6*x, or 6x.

the ones sold at the door are 10 bucks each, and therefore their total cost is 10(x + 206).

now, we know sales in total for both was 6828, therefore,



and surely you'd know what that is.

how many were sold at the door?  well, x + 206.