This is not a function. There are multiple outputs for the same input at 
. A function only has 1 output for every input.
One equation with 3 variables cannot be solved in the sense that you can find "the" 3 values for x, y and m. You can observe that this equation represents a family of straight lines with varying slope (depending on m).
To graph a situation that would involve a linear graph, first determine your x and y axes.
The x-axis will be the independent variable, one that does not change based on other variables. An example is time.
The y-axis, the dependent variable, depends on the independent variable.
The model equation for a linear line is y = mx + b.
"m" is the slope, and the "b" is the y-intercept (where the graph crosses the x-axis at x=0).
For example, a situtation could be that Joe starts with $10 in his account and adds $5 every day to his account.
The x-axis is time in days.
The y-axis is amount of money in his account.
The slope, or rate of change is 5.
The y-intercept, the amount of money he has at x=0 (0 days) is $10.
The equation would be y = 5x + 10
To draw this, plot the y-intercept at (0, 10), and the next point would be 5 units up and one unit to the right because the slope is 5, or 5/1 (remember slope is rise over run: "rise" up 5 and "over" to the right 1).
Im only doing this for. Points so id say probably around at least 5
C
Because .75 times 9 would give you the price of the books and then you would have to add C, the amount left to get to 20.
