a number of two digits of which tens digit exceeds the units digit by 3. the number is 7 times the sum ot its digits find the number.
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Let unit digit of number be x and tens digit of the number is y.
Now the original number is 10y +x .
(Case -1)
y = x+3
so , y -x =3 _eq.1
(Case -2)
(x+y)7 =10y +x
7x +7y =10y-x
6x-3y = 0
Now elimination method,
(y-x =3)6 , (6x-3y=0)1
-6x+6y = 18
6x-3y = 0
___________
0+3y = 18
y = 6.
Now put value of y into equation 1.
6 -x = 3
-x = -3
x= 3
Therefore original number is 10(6) +3 = 63 .
Now the original number is 10y +x .
(Case -1)
y = x+3
so , y -x =3 _eq.1
(Case -2)
(x+y)7 =10y +x
7x +7y =10y-x
6x-3y = 0
Now elimination method,
(y-x =3)6 , (6x-3y=0)1
-6x+6y = 18
6x-3y = 0
___________
0+3y = 18
y = 6.
Now put value of y into equation 1.
6 -x = 3
-x = -3
x= 3
Therefore original number is 10(6) +3 = 63 .
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