We're given the slope of a line and one point on the line (the origin: 0,0). From this, we can determine every other point on the line. The most direct way to find x and y involves solving for each individually.

We know that slope (1/2, in this case), is equal to the change in y divided by the change in x. Since we know that the line passes through (0,0) and (x,1), we can solve as follows:
1/2 = (1 – 0)/(x – 0)
1/2 = 1/x
x = 2
Use the same approach to solve for y:
1/2 = (y – 0)/(10 – 0)
1/2 = y/10
y = 5
Thus, x + y = 2 + 5 = 7, choice (B).