Question

the sum of a two digit number is 7, after interchanging the digits new no. formed is 25 less than double of the original number, then find original number​

Answer 1

Step-by-step explanation:

Let the tens digit be x

Let the ones digit be y

Now,

Sum of the digits=7

or, x+y=7

or, x =7-y

Here,

The original no. is 10x+y

After interchanging,

10y+x

A.T.Q

10y+x=2(10x+y)-25

=> 10y+x=20x+2y

=> 8y = 19x-25

=> y = (19x-25)/8

=> y = {19(7-y)-25}/8

After this substitute the value of y in first equation