Question

$N$ is a two-digit number such that the number formed by reversing the digits of $N$ is $18$ less than $N$. If the units digit of $N$ is $5$, find its tens digit.

Answer 1

$N=y\times 10+x$

$x\times 10+y=y\times 10+x-18$

$x=5$ (given)

$50+y=10y+5-18$

$50-5+18=9y$

$63=9y$

$y=7$

ten's digit $=7$

$N=75$