40 dollars per 5 students=9 dollars per 1 student
divide both sides by 5.
Answer:
Equation is
where
denotes number of cups of orange juice needed by Sam.

Step-by-step explanation:
Let
denotes number of cups of orange juice needed by Sam.
Number of cups needed to make punch 
Number of cups with Sam 
Therefore,

10 + f = 10
-10 -10
f = 10 - 10
f = 0.
Step-by-step explanation:
2.10/0.77=2.72$
dollar per kg
2.2/1=2.2lbs
$2.72/2.2lbs
1.239$/1lbs