First learn to do some calculations by hand for simple systems.

You have to start over, beginning with a working simple system.

As you can see, this is a very simple system.

However, it is possible to obtain quite good results from simple systems.

The goal of these basic rules is to present a simple system first.

To write down their numbers, they had a very simple system.

This simple system would save money and increase the quality of education.

It was hard work, although they used a very simple system.

It took him quite a while to explain the simple system she should use in the future.

A pretty simple system, even if nobody had yet been able to explain it.