An equation that has infinitely many solutions is an equation where no matter what number you plug in for the variable, it will always be right
An example would be this:
5x + 1 + 2 = 5x + 3
No matter what you plug in for x, the equation will always remain equal on both sides
Let’s say x = 3
5 (3) is 15
15 + 1 + 2 is 18
5 (3) is 15
15 + 3 is 18
No matter what you plug in for x, both sides of the equation will remain equal
Hope this made sense
