ACT Math Practice Question: Digits and Place Value

Try this ACT math practice question on digits and place value:

If $t$ and $u$ are the tens and units digit of a positive integer $n$, and the number that results after reversing the digits of $n$ is $18$ more than $n$, then which of the following gives $t$ in terms of $u$ ?

1. $\quad 10-u$
2. $\quad u-2$
3. $\quad u-1$
4. $\quad u+1$
5. $\quad u+2$