Answer:
there are no solutions
Explanation:
In y=-3x+7, -3 is the slope, and 7 is the y-intercept. In 3x+y=4, this equation also equals -3x+4=y. So, -3 is the slope, and 4 is the y-intercept. Once you graph the equations(as seen in the picture below) you should find where the lines intersect. Although, the lines are parallel since the slopes are the same.