Answer:
93
Step-by-step explanation:
Let's set this up with a system of equations.
Represent hamburgers with h, and cheeseburgers with c.
The shop sold 279 total, so our first equation is h+c=279.
The cheeseburgers were 2x the hamburgers, so c=2h.
Now we have our system.
h+c=279
c=2h
Use substitution to solve.
h+c=279
h+2h=279
3h=279
h= 93
93 hamburgers were sold on Monday.
