If the average (arithmetic mean) of a and b is 30 and the average of b and c is 60, what is the value of c − a?  Choose the correct option:
A) 25  B) 60  C) 90  D) 140  E) It cannot be determined from the information given.
-(a + b = 60)   b + c=120   c-a=60   B. 60
<result>B</result>
If the average (arithmetic mean) of a and b is 30 and the average of b and c is 60, what is the value of c − a?