For a school fundraiser troy sold 28 bags of popcorn and 40 candy bars and made 282. jake sold 17 bags of popcorn and 20 candy bars and made 160.50. what was the cost of a bag of popcorn

Assuming the cost of a bag of popcorn is p and that of candy bars is b, then;
Troy ; 28p +40b = 282
Jake; 17b + 20b = 160.50
Solving the two equations simultaneously,
   20(28p +40b =282)
   40(17p + 20b =160.5)
we get;
   560p +800b = 5640
   680p + 800b = 6420 subtracting to eliminate b;
              -120p= -780
                     p = 6.50
Replacing the value of p in either equation to get b;
          17 (6.5) +20b =160.5
                         20b = 50
                              b = 2.50
Therefore the cost of a bag of popcorn is 6.50