#56. 57: Plot it to visualize it. Use the distance formula to find the length of each side using the end points of each side.
#61-64: Picture what you'd be doing in each situation. Remember, if you are covering something, it will an area situation. If you are going around something, it will be a perimeter situation.
#68, 69: Don't let the letters get you...just treat them like variables and remember you can cancel common terms in the numerator and denominator.
#72: Remember, we're looking for the perimeter of the OUTSIDE of the track. Also, look at the picture...what shape is the field part? If you pulled that out, what would be left?