Find an equation for the line passing through the points (-3,1) and (9,7)

The you find this is by first finding the slope. You do this by finding the difference between both x values and then both y values. You get 12(x), 6(y) then write it as a fraction. it is 12/6 which simplifies to 2. 2 is our slope. then you write it out in slope intercept form (y=mx+b) and plug in your numbers. pick one set of original points an put them in to x and y. now you just solve for b. this gives you -9 as b. you put it together to get
y=2x-9
hope this helps :)