If the average (arithmetic mean) of a and b is 210, and the average of b and c is 160, what is the value of a − c?
Options.
A) −220  B) −100  C) 100  D) 135  E) It cannot be determined from the information given
Question: a - c = ?   (a + b)/ 2 =210 ===&gt; a + b =420   (b + c)/2 = 160 ===&gt; b + c = 320   (a + b) - (b + c) = 420 - 320 ===&gt; a + b - b - c = 100 ===&gt; a - c =100   Answer: 100
<result>C</result>
If the average (arithmetic mean) of a and b is 210, and the average of b and c is 160, what is the value of a − c?