Let c is the number of CDs and d is the number of DVDs.

The cost of one CD is 10 dollars and the cost of one DVD is 13 dollars.

The cost of c CDs is 10c dollars and the cost of d DVDs is 13d dollars.

The total cost spent on these items is 40 dollars.

Therefore, this situation represent the inequality .

The graph of the inequality is the shaded region, so every point in the shaded region satisfies the inequality.

The graph of the equation is the boundary of the region. Since the inequality , the boundary is drawn as a solid line to show that points on the line satisfy the inequality.

To graph the boundary line, find the x - intercept and y - intercept of the line.

The y - intercept is the value of y, when x = 0.

To find the y - intercept, substitute the value of in the original equation.

Divide each side by 13.

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The y - intercept is , so the graph intersects the y - axis at.

The x - intercept is the value of x, when y = 0.

To find the x - intercept, substitute the value of in the original equation.

Divide each side by 10.

Cancel common terms.

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The x - intercept is 4, so the graph intersects the x - axis at.

To draw inequality follow the steps.

1.  Draw a coordinate plane.

2.  Plot the points and draw a line through these points.

3.  To determine which half-plane to be shaded use a test point in either half-plane. A simple choice is .

Substitute the value of in the original inequality.

.

4.  Since the above statement is true, shade the region that contains point .

The inequality graph is