If the average (arithmetic mean) of a and b is 80, and the average of b and c is 180, what is the value of a − c?	Choose one:
A) −220 B) −200 C) 100 D) 135 E) It cannot be determined from the information given
a+b = 160   b+c = 360   a-c = -200.   IMO option −200.
<result>B</result>
If the average (arithmetic mean) of a and b is 80, and the average of b and c is 180, what is the value of a − c?