As x increases by 1, y increases by two. Because of this, you know that this is going to be a linear function. To put it in slope-intercept form we first need to find the slope. The slope is 2 because for each unit change in x, y changes two. The y intercept will be 10. We know this because the y intercept is when x is zero. Because we are given the value for when x is 1 and we know that the y value changes by two, all we have to do is subtract two from 12, which is 10. The function will be f(x) = 2x+10