Plug in (3,-1) into equations to see:
-1=2-3
-1=-1 CHECK
3-2(-1)=2(3)
3+2=6
5=6 NO
This is not a solution.
The answer is eighty/ eighty-two
Let T be the taco, B the burrito, MP the mexican pizza, R the rice, and N the beans.
For the main course we can have the first three.
----- T
------ B
-------MP
Each main course comes with the two sides. So an R branch and a B branch go to each of the taco, burrito, or pizza.
-----T---------R or N.
We expand it to
--------T-----------R
---------------------N
And we repeat it for the rest.
Thus, the tree diagram is
----- T --------R
-----------------N
-----B---------R
-----------------N
----MP--------R
----------------N
