Aposter is to have a total area of 500 square centimeters. there is a margin around the edges of 7 cm at the top and 7 cm on the bottom and sides where nothing is printed. express the printed area a in terms of the width w (in centimeters) of the bottom.

Explanation:

Take a look at the picture I attached you. The Rectangle area is given by:

Where:

The total area of the poster is 5m^2, so:

Isolating h:

 (1)

Now, the printed area would be the product between w and h minus the length of the margins, therefore:

 (2)

Replacing (1) in (2) and applying distributive property:

i don't know that i agree with that but what's the question ?