y = 2x + 7.
The ? is the slope, which represents the rate of change between the y-values and x values. If you take notice of your table, the y-values increases by 2, and the x values increases by 1.
Therefore, as y increases by 2 units, the x increases by 1 = 2/1 = 2.
The slope is the same as rise over run:
Rise = increase in y values
Run = increase in x values.
For the other missing box, that represents the y-intercept, which is the value of y when x = 0. If you look at your table, the first row shows that x = 0 and y = 7. Therefore, the y-intercept is 7.
The complete equation is y = 2x + 7, which is the linear equation in slope-intercept form, y = mx + b.