When calulating the perimeter, you are adding the length of all the sides together. Since the figure is a rectangle, two two pairs of sides will be different lengths. Solving is as follows:
P= 11+11+19.3+19.3 or P=11(2)+19.3(2) =60.6
With area, you need the total amount of mass, so you would multiply two sides. In this case, the two are 11cm and 19.3cm.
You would multiply your total amount, 21.95, by your tip divided by 100, so 0.15. It would look like this: 21.95 x 0.15 = 3.293. Therefore, you would give the waitress a $3.293 tip. I Hope This Helps :)
