There are an infinite number of solutions. Any value can be used
for the variable 'x'. Each one produces a value for 'y', and together,
they make a true equation.
When this equation is drawn on a graph, the graph is a straight line
with no end in either direction. EVERY POINT on the line is a solution
to the equation ... a pair of numbers for 'x' and 'y' ... and you know how
many points there are on a line, don't you ?