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A number consists of two digits whose sum is 9. If 27 is subtracted from the number the digits are reversed. Find the number. Looking to do well in your science exam ? Learn from an expert tutor. Book a free class!

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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