Two numbers are in the ratio 3:4. Their LCM is 84. The greater number is ?

Answer: Option C

Let numbers are = 3x & 4x respectively
LCM = 84 (given)
∴ LCM number = common factor (other factors)
x × 3 × 4 = 12x
⇒ 12x = 84
⇒ x = 7
∴ Number are = 3x = 7 × 3 = 21
4x = 7 × 4 = 28
greater number is 28