If two numbers with HCF = 9 are in the ratio 5 : 7, what is their difference?

Correct option is A

Given:
HCF of two numbers = 9.
The two numbers are in the ratio 5:7.
Formula Used:
If two numbers are in the ratio m:n and their HCF is H, then the numbers are: 
​$$\text{Number 1} = H \times m, \, \text{Number 2} = H \times n. \\\text{Difference between the numbers} = H \times (n - m).$$​​
Solution:
The two numbers are: 
​$$\text{Number 1} = 9 \times 5 = 45, \, \text{Number 2} = 9 \times 7 = 63. \\\text{Difference between the numbers: } 63 - 45 = 18.$$​​