Question

a number consists of two digits whose sum is 9 if 27 is added to the number the digits are reversed find the number

Answer 1

Let the units digit be x and the tens digit be y.
Given that x+y = 9. .....(i)
So the no. Is 10x + y.
If 27 is subtracted from the no., it’s digits are reversed.
So we have
10x + y - 27 = 10y + x
9x - 9y =27
x-y = 3 .....(ii)
Adding (i) and (ii), we get
2x = 12
x = 6
Substituting x = 6 in (i), we get y= 3
Hence, the no. Is 63.

Answer 2

Hey friend..!! here's your answer
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Let the unit digit = x
ten's digit _____= y

x + y = 9_______(1)

Digit = 10y + x

if 27 is added to the number , the digit are reserved

10y + x + 27 = 10x + y
10y - y = 10x - x - 27
9y = 9x - 27
9y - 9x = - 27
y - x = -3 _________(2)


Solving equation 1 and 2

x = 9 - y. ....______3

put the value of x in eq 2

y - (9 - y) = - 3
y - 9 + y = -3
2y = 6
y = 3

put the value of in eq 3

x = 9-3
x = 6

We know that unit and ten's digit is x and y resp.

So that the number is 63


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#Hope its help