Answer:
They let you know the number of numbers there are/will be.
Step-by-step explanation:
Mono, being one, means there will only be one number is the equation.
Bi, being two, means there will be two numbers in the equation.
and tri, being three, means there are three numbers in the equation.
-- The area of the long skinny piece on top is (6 x 33) = 198
-- The length of the dotted line between the top and bottom pieces is (33-21) = 12
-- The area of the bottom piece is (12 x 15) = 180
-- The area of the whole thing is (198 + 180) = 378
-- The perimeter of the whole thing is (33 + 6 + 21 + 15 + 12 + 15 + 6) = 108
42 is 21% of 200. This is because 200*0.21 = 42.