If the average (arithmetic mean) of a and b is 115, and the average of b and c is 160, what is the value of a − c?	Choose the correct choice from the following answers
A) −220 B) −100 C) −90 D) 135 E) It cannot be determined from the information given
Question: a - c = ?   (a + b)/ 2 =115 ===&gt; a + b = 230   (b + c)/2 = 160 ===&gt; b + c = 320   (a + b) - (b + c) = 230 - 320 ===&gt; a + b - b - c = - 90 ===&gt; a - c = - 90   Answer: −90
<result>C</result>
If the average (arithmetic mean) of a and b is 115, and the average of b and c is 160, what is the value of a − c?