Answer: y=2x+8
Explanation:
First let's understand what some variables mean.
x is your x value.
y is your y value.
Let's say you have two coordinate points. (1,2) and (9,8)
If the equation had x1, that means you would look at your first coordinate point, (that's what the 1 stands for ;)) and the x value of the coordinate. So in this example, x1 would be 1.
The applies to x2, y1, and y2 as well.
m is typically your slope.
b is your slope intercept.
To find the answers to these equations, you can apply the slope formula which is (y2-y1)/(x2-x1). Then, you would plug the slope as well as a coordinate point into point-slope form, y-y1=m(x-x1). And then convert the point-slope form into slope-intercept form, which is y=mx+b.
This might seem confusing, but after some practice you'll understand.
Let's look at the first problem. Let's use the first two points, (x and y pairs.)
We have (2,12) and (4,16). We can use the slope formula, and substitute in our points. (16-12)/(4-2)=4/2=2 Our slope is 2.
Now we can substitute the slope, and any point of our choice into point slope form.
y-12=2(x-2)
y-12=2x-4
y=2x+8
Edit: Just to clarify, because the slope intercept form is y=mx+b, and b stands for the y-intercept, your y-intercept would be 8.
Hope this helps!