My answer to this personally depends on the data given. We all know a graph would show visually a better representation. Making it much easier to see the information given to us. But, yet on the other hand, an equation lets you get whatever data points you are truly looking for with any range.

If 2 quantities are abstract, and you like pure precision, you can find more data from a simple equation.

So if your trying to show a linear relationship between two quantities a graph is better when working with data to reveal your points, or if you just want to show visually the relationship between the two quantities. If your trying to be like Albert Einstein and want that 10th digit of precision, you will probably fall back on the equation, especially if the equation is the source of the data instead of an approximation of it. Go Albert Einstein..

If 2 quantities are abstract, and you like pure precision, you can find more data from a simple equation.

So if your trying to show a linear relationship between two quantities a graph is better when working with data to reveal your points, or if you just want to show visually the relationship between the two quantities. If your trying to be like Albert Einstein and want that 10th digit of precision, you will probably fall back on the equation, especially if the equation is the source of the data instead of an approximation of it. Go Albert Einstein..