I don't know if this is the right place to post it, but I'm basically doing a problem on the common factors (5.2 of Mathematics 10 by McGraw-Hill Ryerson, question 14) in which I have to "write a factored expression to represent the area of the metal plate around the dials, shaded in grey." So, there's 4 squares grouped up together to form the "metal plate"(so basically a rectangle), and there are four circles in the metal plate, which are basically the dials. I can't get my mind around to complete this question, there's no lengths or widths. I basically started by doing 4(r^2) - 4(πr^2) and now I don't know where to go.