For the missing x value in the table, replace y by -2.5 in the equation and solve for x:
y= 1/2x - 5
-2.5 = 1/2x-5
-2.5+5 = 1/2x
2.5 = 1/2x
2.5/ (1/2) = x
x= 5
For the missing y values replace by the corresponding x values and solve:
x= 7
y= 1/2(7)-5
y= 3.5-5 = -1.5
x=10
y= 1/2 (10) -5
y= 5-5
y=0