We know that b is 6 because that is the y-intercept.
However to find m we need to see how much the x coordinates skip on the table and the y coordinates. We can see that x coordinates skip by 5s and the y corrdinates skip by 3. We than divide 3/5 to get o.6 and we get the equation. This video, tittled "Writing A Linear Equation From A Function Table" explains it much better than I can.