As you can see from the chart, when x increases by 10, y increases by 20. We can assume that because of this porportional relationship, when x increases by 1, y will increase by 2. We're looking for the y-intercept, in other words we need to get x to 0. So if we subtract x by 16, we must take 32 away from 44(the y-value), because of this porportional relationship. That gets us an x value of 0, and a y value of 12. (0,12) would be the y-intercept.
