When writing an equation of a line using slope-intercept form: y=mx+b, the slope of the line would take the place of m, and the y-intercept would take the place of b. Just substitute these variables for the slope and y-intercept to find the equation of the line.
I think it's just 2 numbers you add together to get that number. for example number 6 you could add 10 and 5 in the circles to get 15 then you add 15 and 4 to get 19