The LCM of two numbers is 30 and their HCF is 5. One of the numbers is 10. The other is:

15
Because, First number $latex \times$ Second number = LCM $latex \times$ HCF
Let the Second Number be x.
∴ 10x = 30 $latex \times$ 5
$latex =>x=\frac{30\times 5}{10}=15&s=1$
Hence option [B] is the right answer.