The answer is 500 becuase it is
Let

be the number of rides Chandler takes in a month. Then the cost with the MetroCard is still $81, but the cost without the MetroCard is

. So we can set up an equation representing what we want: "The cost with a MetroCard of r rides in a month is less than the cost without a MetroCard." In equations,

Thus, at a minimum, Chandler must take 41 rides for his MetroCard to be cheaper than not having it.
987.76 Hz please thank you
-216x^9 y^18 is a perfect cube