Figure out what the equation for each line is by substituting values of x and y on a point on that line, using y=mx + c. Then choose the point on the line where x is the same for both lines (0.5, 0) and find the value for y for each. Then, just divide the value of g (x) by the value of y (x), so k= g (x) / y (x). Hope that helps ;)