an article marked at rs.8000 is sold at rs.6689.60 allowing a some discount and

Option A. The solution set is (4,5)

Step-by-step explanation:

Solve the equation for y to obtain the form of the equation of the line.

You have:

y=-x+9 (The slope is -1 and the y-intercept is 9)

y=x+1 (The slope is 1 and the y-intercept is 1)

When you graph it you obtain the graph shown in the figure attached.

The solution is the intersection of the lines.

Then, the solution set is (4,5)