If the average (arithmetic mean) of a and b is 45 and the average of b and c is 70, what is the value of c − a?	Choose the correct choice from the following choices
A) 25  B) 50  C) 90  D) 140  E) It cannot be determined from the information given
the arithmetic mean of a and b =(a+b)/2=45 -- a+b=90 --1   similarly for b+c=140 --2   subtracting 1 from 2 we have   c-a=50;   ANSWER:50
<result>B</result>
If the average (arithmetic mean) of a and b is 45 and the average of b and c is 70, what is the value of c − a?