.
The sum of the digits of the two number is 5.
If 10 times the tens digit is added to 4 times the unit digit,
the number obtained is in the reverse order of the digits of the original number. find the number?
~~~~~~~~~~~~~~~~~~~~~~~~~~~
The equations are
t + u = 5, (1) (where t is the "tens" digit, u is the "units" digit.)
10t+4u = 10u + t. (2)
Simplify:
t + u = 5,
9t = 6u.
t = 5-u,
9*(5-u) = 6u,
45 - 9u = 6u,
45 = 15u ---> u = 3, t = 2.
The original number is 23.