Question 1824
this question is very odd...you are given info that you cannot use...the $850 and the "assume x=10" bit. Are you sure there is not more to this?

anyway... draw a square to represent the patio then draw a slightly larger one around it to reperesent the brick border.

the larger square has length 2x, so the shorter square must have length 2x less 2 lots of bricks, ie less 16 inches...so the patio side has length (2x-16) and therefore the area is given by {{{(2x-16)^2}}}


cheers
Jon.