Answer:
If we have a system of linear equations:
y = a*x + b
y = c*x + d
And the graphs of the equations are the same line, this means that both lines have the same equation, then:
a = c and b = d.
Then we have only one equation (but repeated) and two variables, then we have infinite solutions for our system.
Another way to see this is:
When we have a system of linear equations, the solution is the point where the lines intersect.
But if both lines are the same line, then the lines intersect in infinite points, then we have infinite solutions.
