Bonjour je n’arrive pas à mon exercice de math, quelqu’un pourrez m’aider s’il vous plaît:

Write a formula expressing...

a. The total value of p twenty dollar bills, q ten dollar bills
and r five dollar bills.
b. The perimeter of a rectangle whose lenght is three units
longer than the width. You can use only one letter.
c. The area of a rectangle whose length is twice the width.
d. The area of the net* of a cube whose edge is a.
e. The area of the net* of a cylinder whose height is h and
radius is r.