We know that a number must be decreased by four. Let's break it up a little.
Nine times <em>some </em>number. We don't know what nine will be multiplied by, so we will just write a placeholder number: x. This number will be multiplied by nine. So it will turn into 9x.
We must decrease (subtract) from this by four. Subtracting 9x by four can be written as 9x - 4.
The length is about 28 more than three times the width. Denoted as (a) width, and as (b) the length. Then move on to lay the system of equations, as done below:
The short side has a length of 10 cm, and 58 cm long.