Each time x goes up by 2, y decreases by 4
This indicates we have a linear function. The slope in this case would be
m = rise/run = (change in y)/(change in x) = -4/2 = -2
The y intercept can be found by following these steps
y = mx+b
0 = -2(5)+b
0 = -10+b
10 = b
b = 10
Therefore, the equation of this line is y = -2x+10. Plug in something like x = 1 and it should lead to y = 8. The same applies for any other column of x,y values.