So, if we end up with x = something, we have one answer. If we end up with an untrue equation, like 0 = 5, we have no solution, but if we end up with 0 = 0, we have infinite solutions.
5(x + 2) = 5x + 10
Because 5 is a factor being multiplied by x + 2, we can divide both sides by 5.
x + 2 = x + 2
x = x
0 = 0
Well, there ya go. We have an infinite number of solutions. No matter what value we give x, the equation will be true.
Let's try other examples.
5(x + 3) = 5x + 10
x + 3 = x + 2
x = x - 1
0 = -1
Well, that's not true, so we have no solution. We can't find any value for x to make the equation true.
5(x + 2) = 20
x + 2 = 4
x = 2
Hey, this has one solution that makes the equation true. Any other value for x would not make our equation true.
Hope this helps!