# The sum of a 2 digits of 2 digit number is 7.if the digits are reversed,the number formed is 9 less than the original number. what is the original number?

1
by santhosh2

Log in to add a comment

by santhosh2

Log in to add a comment

the digit at tens place be y.

therefore the no. is 10y + x

if the digits are reversed then no. is 10x + y

a/q

x + y = 7 .....(i)

10y + x - (10x + y) = 9

10y + x - 10x - y = 9

9y - 9x = 9

9 (y - x) = 9

y - x = 1 .....(ii)

on adding eq. (i) and (ii), we get

y + x = 7

y - x = 1

2y = 8

y = 4

Now sustitution y = 4 in eq. (i)

x + 4 = 7

x = 3

As we know that no. is 10y + x

so, the no is

10(4) + 3 = 40 + 3 = 43

so, the original no. is 43