Hey there!
Let's define that "number" as x.
If we have 5 times that number, we have 5x. Now, since the problem says minus nine, we have to subtract nine to give us,
5x - 9
Now, we have to look at our next keyword, is. "Is" signifies an equation and an equals sign. Therefore, this expression equals twenty six. We have:
5x - 9 = 26
Hope this helps!