Answer:
The answer to your question is These lines have infinite solutions because they are the same line.
Explanation:
Equation 1 y = -3x + 12
Equation 2 x + 1/3y = 4
Solve for y
Equation 1 y = -3x + 12
Equation 2 y = -3x + 12
See the graph below
From the graph, we conclude that the lines are the same so they have infinite solutions.
If they have crossed in one point that would have been the solution.