A number consisting of two digits is seven times the sum of its digits. when 27 is subtracted from the number the digits are reversed. find the number
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The first eq. Will be 10x+y=7(x+y)
The original no. Is 10x+ y
The second eq.
Will be 10x+y-27=10y+x
On simplification we get
3x-6y=0
9x-9y=27
By elemination method we get
-9y+18y=27
9y=27
y=27/9
=3
Substituting the value of y in eq. 1 we get
3x-6*3=0
3x-18=0
3x=18
x=18/3
=6
So the original number is 63
The original no. Is 10x+ y
The second eq.
Will be 10x+y-27=10y+x
On simplification we get
3x-6y=0
9x-9y=27
By elemination method we get
-9y+18y=27
9y=27
y=27/9
=3
Substituting the value of y in eq. 1 we get
3x-6*3=0
3x-18=0
3x=18
x=18/3
=6
So the original number is 63
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