If the average (arithmetic mean) of a and b is 150, and the average of b and c is 90, what is the value of a − c?	Choose the correct answer: A) −220 B) −100 C) 120 D) 135 E) It cannot be determined from the information given
a+b = 300   b+c = 180   a-c = 120.   IMO option 120.
<result>C</result>
If the average (arithmetic mean) of a and b is 150, and the average of b and c is 90, what is the value of a − c?