students are selling pop for $2 each and candy bars for $1 each the students made $31 total and sold 20 items total how many items of each did they sell

Question

 its solving systems of equations using substitution

Answer 1

Let p stand for the number of pop cans you sell and c stand for the number of candy bars you sell. Then p+c=20. Additionally, 2p stands for the amount of money you spend on pop and 1c stands for the amount of money you spend on candy bars. So 2p+1c=31. So we have a system of equations we need to solve.

              p+c=20

              2p+c=31

Solve the first equation for c. So we subtract p from each side and get c=20-p. Next, substitute this in for the second equation.

              2p+(20-p)=31

Now we can solve the equation for p. Subtract 20 from both sides, and combine 2p-p to get:

              p=11

If p=11, then 11+c=20 (from the first equation). Thus, c=9.