Hi Jocelyn M.
-(1/2)x + y = -7
For your line you are given a point (10,-2) and the slope m=1/2
Use this information to get started since you have a slope you can use the Slope Intercept Form
y=mx + b
y=(1/2)x + b
Use the coordinates of the point given to solve for b
-2 = (1/2)10 + b
-2 = 5 + b
Subtract 5 from both sides
-2 - 5 =b
-7 =b
Now we have the line in Slope Intercept Form
y = mx + b
y = (1/2)x -7
Just subtract (1/2)x from both side to get it into Ax + By = C
-(1/2)x + y = -7
You can check by plugging the x coordinate of the point (10, -2) to see if it yields the y coordinate
-(1/2)10 + y = -7
-5 + y = -7
Add 5 to both sides of the equation
y = -7 + 5
y = -2
I hope you find this useful.