Optimisation C1

A rectangle has one side x cm and its perimeter is 44cm. Show that the area of the rectangle Acm^2 is given by A = 22x - x^2.

Ive tried drawing out the rectangle and solving it by looking at it but nothing seems to be working out....I couldnt do optimisation last year either...grr.

Any help?

Ok ive figured that one out and a few others now ive come to this:

Pat has £120 to spend on a decorative fence to enclose a rectangular garden. The fencing for 3 sides costs £2 per metre and the fencing for the fourth side which is of length x metres costs £3 per metre.

Given the rectangle has dimensions x metres by y metres show the 5x - 4y = 120

I dont understand where they've got the 5x and -4y from...