How to excel on a formula based on a picture chart

For example, my equation is y = 30-3x, 0 <X <10, on how to excel in the drawing? According to the equation and can not come to a pile of data and mapping.

Geometer's Sketchpad, the most good at this issue, particularly for middle school students practical, the software is very small, to meet the students of physics and mathematics, drawing a lively and dynamic can be observed.a variety of Software, use a different, excel spreadsheet, focusing on data processing, mapping is not his strength, “ran a one-China”, or “The Geometer's Sketchpad” the best.