The two plans don't fall directly on a same prive, but after 3 hours of Data usage plan B costs more than plan A
After three hours plan A= $18.60
While plan B after three hours =$19.09
That means 3 hours has to pass before plan B costs more, That is 180 minutes
The rule per hour is $1.2 per hour for plan A and $4.8 per hour for plan B
The number of friends change the total number of canvases needed, so the number of friends is the independent variable, so the answer is B.
The correct answer is 21 simply because 21 is a multiple of 3 and a multiple of 7, other answer does not hold this conclusion.
The answer would be A 20c/d
