What is an area model and standard algorithm

Adeli charges the same price, $5.50, for all of its different sandwiches. if a company ordered n sandwiches for a luncheon, which equation could be used to find the total price, p, that the deli charged for the sandwiches? a- n/5.50=p b-5.50n=p c-5.50/n=p d-5.50+n=p

Which of the fallowing best completes the sequence 5,10,15, a) 30 b) 22 c)25 d)35

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters