First setup the system of equations for the given case.
Let sandwich=x
and delivery fee =y
Equations are:
4x+y=33 Equation 1
8x+y=61 Equation 2
Subtract equation 1 from 2.
4x=28
x=7
Now substitute value of x in equation 1.
4(7)+y=33
28+y=33
y=5
So cost of single sandwich=$7 and Delivery fee=$5
Now cost of 12 sandwiches:
12x+y=85
Put y=5
12x+5=85
12x=80
x=6.67 which is less than 7. So, They are not able to get 12 sandwiches for $85.