Answer:
13 hamburgers
9 hotdogs
I see the person that also gave you an answer never explained how they got the answer. I thought you might like an explanation
Explanation:
Let x = no. of hamburgers
y = no. of hotdogs
(1) x + y = 22 (2) 3.5x + 2.5y = 68
y = 22 - x 35x + 25y = 680
35x + 25(22 - x) = 680
35x + 550 - 25x = 680
10x + 550 = 680
10x = 130
x = 13 hamburgers
y = 22 - x = 22 - 13 = 9 hotdogs