Question 465764
Perimeter means to add up all of the sides.  Since it's a rectangle, you have 2 sides that have length b + 7, and 2 sides with length b.  So, the polynomial is {{{(b+7)+(b+7)+(b)+(b)}}}.  Simplified, that's 4 b's plus 2 7's: {{{4b+14}}}.

Area is length times width, or base times height...basically, one side times the other.  So, for you: {{{(b)(b+7)}}}.  Distribute your b and you have {{{b^2+7b}}}.