Substitution refers to "substituting" one variable in one equation for the same variable in another.

For example:

In -7x + y = 60, let's solve for y: y = 7x + 60 (I added 7x to both sides)

With this, we have

y = 7x + 60

6x + 8y = -16

Since y = 7x + 60, we can plug this in for the "y" in 6x + 8y = -16, and we get:

6x + 8(7x + 60)= -16

Now we have one equation with only "x"s. Solving for x, we get:

6x + 56x + 480 = -16

62x = -496

x = -8

Now we can solve for the value of y in y = 7x + 60 since x = -8

y = 7(-8) + 60 = -56 + 60 = 4

So we have x = -8, y = 4, which is the point (-8,4)