Integers and place values?

Question

Suppose the tens digit of a whole number between 80 and 90 is greater than the ones digit,but less than twice the ones digit. If the integer is even, what is it's value?

Answer 1

Ok so we know $80 < x <90$, so $x=8a$ where $a$ stands for some integer between 0 and 9. We know $a < 8$ because of the first condition.

We know have $a=1 , \dots ,7$, but the integer is even, meaning we get left with $a=2,4,6$. Using the last condition now, the tens digit must be strictly less than $2a$, meaning that $a=6$ is the only solution.

I believe the number you are looking for is $86$!