What operating system was most commonly used by early personal computers?

Write a program that uses a widgetviewer object to do the following: generate two random integers between 1 and 9 (inclusive). name one of them x, the other y. display them to the user using jlabel objects. create a jlabel object displaying the text "enter an operation number." create a jtextfield for the user's input. create a jbutton displaying the text "press here when you've entered your operation." use addandwait to add it to the widgetviewer object. when the user clicks the jbutton, evaluate operation in the following order to determine the one and only mathematical operation to perform on x and y. use a jlabel to display the result. if operation is between 1 and 10 inclusive, add x and y. if operation is evenly divisible by 4, subtract y from x. if operation is evenly divisible by 5, use integer division to divide y into x. if operation is an even number, use floating point division to divide y into x. if none of the other tests on operation apply, multiply x and y. note: operation can be negative or zero.

Aconstruction company is creating a powerpoint presentation describing how they calculate costs during each construction step. they plan to email this presentation to clients. the individual clients will be watching the presentation slide show on their own personal computers. what is the most important formatting step the company should take to make the text readable and pleasing to the eye?

All of the following are characteristics that must be contained in any knowledge representation scheme except