The answer k is n divided by 6
Last one 7 and 3
9(7)+20(3)>120
63+ 60
123>120
Says 123 minutes is longer than 120 that's why it is that answer
You would pay 80% of the original price because 1/5 is 20% and you would subtract 20 from 100 to get 80 as your answer
Hope this Helps :3
ANSWER
D.

EXPLANATION
The given function is

Comparing to the general form of a trigonometric sine function,


The amplitude is absolute value of A


The period is given by



is a shift to the right of 4 units.
and

is an upward shift of 9 units
Therefore the phase shift is (4,9).
The correct answer is D