If the average (arithmetic mean) of a and b is 140, and the average of b and c is 100, what is the value of a − c?
Choose the correct choice.
A) −220  B) −100  C) 100  D) 135  E) 80
a+b = 280   b+c = 200   a-c = 80.   IMO option 80.
<result>E</result>
If the average (arithmetic mean) of a and b is 140, and the average of b and c is 100, what is the value of a − c?