Answer :
Hey there! I'm happy to help!
Let's call our hamburgers h and our cheeseburgers c and set up a system of equations to solve.
c+h=512
c=3h
Let's plug this value of c into the first equation to solve for h.
3h+h=512
4h=512
Divide both sides by 4.
h=128
Therefore, 128 hamburgers were sold on Wednesday.
Have a wonderful day! :D