The ratio of a to b to c is 2 to 3 to 4, and a, b, c are positive integers. If the average (arithmetic mean) of the three numbers is 42, what is the value of a?
Choose the most appropriate option:
A) 24 B) 25 C) 28 D) 30 E) 32
Let a=2k, b=3k, and c=4k.   a+b+c = 2k+3k+4k = 9k   Since the average is 42:   9k/3 2 +3 +4= 
<gadget id="calculator">2 +3 +4</gadget>
<output>9</output>
9k   Since the average is 42:   9k/3= 42   3k = 42   k=14   Then a=28.   The answer is 28.
<result>C</result>
The ratio of a to b to c is 2 to 3 to 4, and a, b, c are positive integers. If the average (arithmetic mean) of the three numbers is 42, what is the value of a?