John sells hamburgers for $3 each and cheeseburgers for $3.50 each. one afternoon, he sells a total of 24 burgers for $79. how many hamburgers did he sell?

Let the hamburgers be x and cheese burgers be y.

x + y = 24
3x + 3.5 y = 79

x = 24 - y.

Substituting the value of x,

3( 24 - y) + 3.5 y = 79

 72- 3y + 3.5 y = 79
72 + 0.5 y = 79

0.5y = 79 - 72 = 7
1/2 y = 7

thus, y = 7 * 2 = 14

Substituting the value for x,

x + y = 24
x + 14 = 24
x = 24-14 = 10
Thus, x = 10.

Thus, she sold 10 hamburgers and 14 cheeseburgers