Number of burgers = b = 36
Number of hot dogs = d = 52
We know that b + d = 88 (they sold 88 items)
And 4.5b + 3.25d = 331 (price • number = money made)
So we will solve the first equation for b in terms of d, then substitute that in the second equation to sell for a numerical value of d.
b + d = 88
b = 88-d
4.5(88-d) + 3.25d = 331
396 - 4.5d + 3.25d = 331
-1.25d = -65 (divide both sides by -1.25)
d = 52
Now plug that into the first equation to get a numerical value for b.
b = 88 - d
b = 88 - 52
b = 36
Checking the math:
4.5(36) + 3.25(52) = 162 + 169 = 331
Please lmk if you have any questions