Question

The sum of a two digit number and the number obtained by reversing the order of the digits is 187. If the digits differ by 1, then what will be the number?

(a) 67

(b) 54

(c) 89

(d) 67

I have been asked this question during an online interview.

Enquiry is from Solution of Two Linear Equations in Two Variables in Different Methods in division Pair of Linear Equations in Two Variables of Mathematics – Class 10

Answer 1

Correct option is (c) 89

The best I can explain: Let the two digit number be 10x+y

The number obtained after reversing the digits will be 10y+x

10x+y+10y+x=187

11x+11y=187

x+y=17     (1)

Also, x-y=1     (2)

Adding (1) and (2)

2x=18

x=9

Substituting in equation (1), 9+y=17

y=8

The number is 89 or 98.