Two lines, a and b, are represented by the following equations:
line a: 3x + 3y = 12
line b: x + y = 4
which statement is true about the solution to the set of equations?
it is (12,4).
there are infinitely many solutions
it is (4,12).
there is no solution

Let's simplify equation Line A

3x + 3y = 12

3(x + y) = 3(4)

Divide 3 on both sides

x + y = 4

Now let's compare Line A and B again.

Line A: x + y = 4 
Line B: x + y = 4 

Both lines are exactly the same!

So that means any point that works in Line A should also work in Line B! That means it has infinitely many solutions! :)

Your answer is: 
There are infinitely many solutions.

I hope that helps! :D