What is the equation of the line that goes through the given points? (–3, 1), (6, 4)

first you find the slope (rise/run). Which in this case is 3/9 or 1/3.

then you find the y intersept (where the line crosses the y axis). for your problem it is 2. 

finaly you write it in y=mx+b form. the m is the slope and the b is the y intersept.

So now you just plug in the information you found for you problem. 

so your equation is y=1/3x+2