How do i solve 2x-y = -1 and 3x + y = 6 using substitution?

To use substitution, you want to substitute something for another variable. So lets take the first equation and solve for y

2x - y = -1

2x = y - 1

2x + 1 = y

Now we can substitute 2x + 1 for y in the other equation

3x + 2x + 1 = 6

5x = 5

x = 1

now that we have x, we can get y

2(1) - y = -1

2 - y = -1

2 = y - 1

3 = y

So x = 1 and y = 3

there are infinitely many solutions.