Convert 65,000,000 to scientific notation

If a 36 inch yardstick casts a 21 foot shadow, how tall is a building whose shadow is 168 feet? what is the scale factor

Acomputer store buys a computer system at a cost of $370.80. the selling price was first at $ 618, but then the store advertised a 20 % markdown on the system. answer parts a and b. a. find the current sale price.

Can someone explain to me how to do