Of three numbers, the third is thrice the second and the second is 5 times the first. If their average is 105, the smallest of the three numbers is:  Choose the most appropriate option
A) 18
B) 15
C) 20
D) 21
E) 22
Explanation:   Let first number be x.   So,2nd no. = 5x &amp; 3rd no.=15x.   So,x+5x+15x=105× 3 = 234.   21x = 315   x = 315/21   Hence,smallest Number x=15.   Answer: 15
<result>B</result>
Of three numbers, the third is thrice the second and the second is 5 times the first. If their average is 105, the smallest of the three numbers is: