How do I find the value of x or y?

Question

Okay I'm having a little trouble with finding a value of x or y. It's not one of those really really confusing algebra but more simple but I just don't get it. What I'm supposed to do is find the value of x or y so that the line passing through the two points has the given slope. And they give you the ordered pairs. The ordered pairs are, (-2,8), (x,4); m=4/5 So how do I find the x?? And can anybody put a detailed steps of solving it? I know when doing this it's supposed to be something like this

4/5 = 8-4 over -2-x.

Answer 1

m=(y2-y1)/(x2-x1)

4/5=(4-8)/(x+2)

4(x+2)=5(4-8)

4x+8=20-40

4x+8=-20

4x=-28

x=-28/4=-7

Answer 2

They have given you one complete paid ( -2, 8 ), and the slope 4/5.

Anytime you have one point and a slope, use this formula

y - y1 = m ( x - x1)

so,

y - 8 = 4/5 ( x - (-2) )

y - 8 = 4/5 ( x + 2 )

y - 8 = 4/5x + 8/5

y = 4/5x + 48/5

Graph this line,

You will see that x = -7 when y = 4.

There might be an easier way to do this, but its been so long that I don't remember them :(