Answers

2014-05-28T11:15:11+05:30
Let first digit is x & second digit is y.
then the number is (10x + y)
x + y = 3     -------------------------(1)      (given)
7(10x + y) = 4(10y + x)           (given)
2x = y   
put the value of y in equation (1)
3x = 3
x = 1
y = 2
hence number is (10*1 + 2) = 12
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2014-05-28T12:49:26+05:30
seven times a two digit number is equal to 4 times the number obtained by reversing the order of the digits and the sum of the digit is 3 find the number.
Solution :
           let the digit at units place = x
           and the digit at tens place = y
therefore original number = 10y +x
             reversed Number = 10x+y
According to question ,
                 7 (10y +x) = 4 (10x+y) ............(given)
                 70y + 7x = 40x +4y
                 70y - 4y = 40x - 7x
                 66y = 33x
                    2y = x
                 x =2y   ...............(1)

Sum of digits of two digit number = 3 ........(given)
                     x + y = 3
Substitute x in above equation , we get
                   2y + y  = 3
                   3y =3
                   y= 3/3
                   y=1
substitute y in 1 , we get
               x=2*1
                   x=2

Hence original number = 10y+x
                                       = 10*1 + 2
                                       = 10 + 2
                                       = 12

hope this helps you!!!
                  
  
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