A scale drawing is an enlarged or reduced drawing of an object that is similar to an actual object. Maps and floor plans are smaller than the actual size. A scale drawing of a human cell is larger than the actual size.
On a map, the equal sign in 1 in. = 30 mi does not mean that the two quantities are equal, as it would in an equation.
A scale is the ratio that compares a length in a drawing to the corresponding length in the actual object. If a 30-mile road is 1 in. long on a map, you can write the scale of the map in these three ways:
Go here for more. http://www.phschool.com/itext/mgmath_course2/Ch05/05-07/PH_MSM2_ch05-07_Obj1.html
