Question

the sum of the digit of a two digit number is 7 if the digits are reversed the new number is equal to 3 less than 4 times the original number find the original number​

Answer 1

Let the 2 digit no. be 10x+y(in standard form)

so no. formed by reversing digits -

10y+x

According to question x+y=7.....(1)

And 10y+x=4(10x+y)-3

10y+x=40x+4y-3

10y-4y=40x-x-3

6y=39x-3

Now substitute value of x from eq.(1)

so, 6y=39(7-y)-3

6y=273-39y-3

6y+39y=273-3

45y=270

y=270/45 =6

So y=6 and x=7-6=1

So, the number is

10x+y=10*1+6=10+6=16