Answer: B. 
Step-by-step explanation:
The notation to express a dependent variable is given by :-
, where Y is depending variable which is dependent upon x ( independent variable).
The given statement : The distance an airplane travels depends on how much time it spends flying.
Here , Independent variable : Time
Dependent variable : Distance
Then , the notation to express distance (dependent variable) the airplane flies in 20 minutes is given by :-

I'm pretty sure both B and C equal 12 as well
Since the triangle equals 180 and the angels are all congruent
Answer:
easy
Step-by-step explanation:
subtract 3x both side