You are to create $3$ digit even numbers greater than $400$ so think as follows:
It cannot start with a number less than $4$. So let us start with $4$, then you only have one choice left for the last digit, namely $2$. Can you figure out the rest? (you can peek by mouseovering the yellow boxes, but try to figure out yourself first, before you peek)
$3$ different numbers since the first and last digit is determined and you have $3$ other digits to choose from to fill the middle
It can also start with a $5$, in this case it can end with both $2$ and a $4$. I am sure you can figure the rest out ;)
If it ends with a $2$ you have $3$ choices for the middle number, since once again we fixed the first and the last digit and the same is true for when it ends with a $4$
Adding these together you end up with
a total number of $3+3+3=9$ possibilities.
Hope I could help