 # RD Sharma Solutions Class 8 Mathematics Solutions for Linear Equation in One Variable Exercise 9.4 in Chapter 9 - Linear Equation in One Variable

Question 6 Linear Equation in One Variable Exercise 9.4

A number consists of two digits whose sum is 9. If 27 is subtracted from the number the digits are reversed. Find the number.

We know that one of the digit be ‘x’

The other digit is 9-x

So, the two digit number is 10(9-x) + x

The number obtained after interchanging the digits is 10x + (9-x)

10(9-x) + x – 27 = 10x + (9-x)

Upon simplification,

90 – 10x + x – 27 = 10x + 9 – x

-10x + x – 10x + x = 9 – 90 + 27

-18x = -54

x = 54/18

= 9/3

= 3

The two digit number is 10(9-x) + x

Substituting the value of x we get,

10(9-x) + x

10(9 - 3) + 3

10(6) + 3

60+3

63

∴ The number is 63.

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