Can someone with a? will give brainliest

14 you go up to 21 on cost and see what point is rhere or closest under in this case it is 14

A) The greatest number of museum tickets that can be sold for $21 is 14 tickets.

B) Use the equation below:
Rise ÷ Run
You can use (4 tickets, 6 dollars) as one point. You rise up by 6 dollars and run by 4 tickets so now you have to do rise÷run which is 6÷4. That means the answer is $1.50, so one ticket costs $1.50

C)
c= total amount of money
n= number of muesuem tickets bought

c=1.50n
(I believe this is the right answer, I'm not too sure)