Every band member is 15,16, or 17 years old. One third of the band members are 16, and twice as many band members are 16 as 15.
Col A: The number of 17 years old band members
Col B: The total number of 15 and 16 year old band memebers
lets say any arbitrary no for the total band member . since 1/3 the band members are 16 , so lets say total no of band member , Total no = 300
so, no of band ,member whose age is 16 = 300(1/3) = 100.
since, twice as many band members are 16 as 15 that means no of band ,member whose age is 15 = (100/2)= 50
lastly , no of band ,member whose age is 17 = 300-( no of band ,member whose age is 16+no of band ,member whose age is 15)= 300-(100+50) = 150
now col A= 150
COL B = 100+50=150
ans "C"