If the average (arithmetic mean) of 3, 6, and z is less than or equal

If the average (arithmetic mean) of 3, 6, and z is less than or equal to 75, what is the greatest possible value of 3 + 6 + z ? A. 66 B. 75 C.111 D.225 E.234 Got this on GMAC practice exam 5, who knows how to answer this? Bunuel