How many solutions does an equation have when the variable adds out and the final sentence is true?

Infinitely many solutions

Step-by-step explanation:

If we have a system of equation like:

2x+y=4

6x+3y=12

If we make y the subject in the first equation and substitute into the second equation, we get:

6x+3 (4-2x) = 12

We expand to get:

6x+12-6x=12

6x-6x+12=12

Now the variable adds out to give:

12=12

This statement is true so the equation has infinitely many solution.