Question

A two digit number is reversed so the number formed by reversing is 34 more than the thrice of the previous number. One of the two digits is 9 times the other then find the original number.

1. 18
2. 20
3. 22
4. 19

Answer 1

Correct Answer - Option 4 : 19

Given

Reversed number = 3 × original number + 34    

b = 9 × a      ------(1)

where a and b are the assumed digits of the number.

Formula used

Any two digit number can be expressed in the form 10a + b

Calculation

⇒ Let (10a + b) be the number before reversing

⇒ So the number after reversing becomes (10b + a)

⇒  10b + a = 3 × (10a + b) + 34      ------(2)

⇒ Substituting  (1) in (2) gives

⇒ a = 1 and b = 9

∴ 19 is the number before reversing.