Why do we use simple and compound machines?

Question

Why do we use simple and compound machines?

Answer 1

In many instances, the combination of two or more simple machines achieves results that cannot be achieved by a simple machine alone. Such combinations are known as compound machines. An example of a compound machine is the common garden hoe. The handle of the hoe is a lever, while the blade that cuts into the ground is a wedge. Machines with many simple machines combined with each other—such as typewriters, bicycles, and automobiles—are sometimes referred to as complex machines.

http://science.jrank.org/pages/4059/Mach...