To find the missing values, find the slope of the equations. Since both equations are linear, we know that the slope is linear. We can find the slope of the equations by using the equation for slope.
Slope for Y1:
m = (y2 - y1) / (x2 - x1) = (11 - 15) / (-3 - -5) = -4 / 2 = -2
Therefore, for Y1, you can subtract 2 from each previous answer to fill in the column. So underneath 15 would be 13, then 11, then 9, etc.
Slope for Y2:
m = (y2 - y1) / (x2 - x1) = (-12 - -15)) / (-4 - -5) = 3 / 1 = 3
Therefore, for Y2, you can add 3 from each previous answer to fill in the column. So underneath -15 would be -12, then -9, then -6, etc.