Four ninths means 4/9 and of means multiply= 4/9 × 45
=20/1
=20
One of the main reasons you have to show work for math is because your teacher needs to know that you understand the concept. Also, showing work helps your teacher know that you didn't cheat using an online calculator that just gives you an answer.
We need to find the scale factor, which is given as

then, this means that 1 millimeter : 5 meters