Michael and Ming-Wei are selling fruit for a school fundraiser. Customers can buy small boxes of oranges and large boxes of oranges. Michael sold 3 small boxes and 14 large boxes for a total of $203.
Ming-Wei sold 11 small boxes and 11 large boxes for a total of $220. Find the cost of each size box.

L = large boxes S=small boxes
3s + 14l = 203
11s + 11l =220
You can eliminate a variable, I'm going to eliminate s but from the 2 equation since it's easier to do the math. I'm going to multiply the equation by -3. I'm going to multiply the first one by a positive 11.
-33s-33L=-660
33s + 154L= 2233
121L=1573
1573÷121 =13
So one large box equals 13, now find the price of a small by plugging it into an equation.
3s + 14 (13)=203
3s+ 182 =203
203-182=21÷3=7
Now a small equals 7, check if both are correct by putting it into another equation.
11 (7)+11 (13)=220
77+143 =220
220=220
A small equals $7, while a large equals $13.