b + c = 74 (the total number of copies purchased is the sum of black-and-white and color copies)
0.15b + 0.29c = 16 (the total cost is the sum of the cost of black-and-white copies and the cost of color copies)
A customer paid a total of $16 for 74 copies at a print shop. Some of the copies were black-and-white copies, and the rest were color copies. Each black-and-white copy cost $0.15. Each color copy cost $0.29. Which system of equations can be used to find b, the number of black-and-white copies, and c, the number of color copies that the customer paid for at the print shop?
3 answers
Which graph best represents this system of equations and its solution?
`8x-4y=-16`
`3x+15y=-6`
`8x-4y=-16`
`3x+15y=-6`
To graph this system of equations, we first need to rewrite them in slope-intercept form (y = mx + b), which means solving for y:
8x - 4y = -16
-4y = -8x - 16
y = 2x + 4
3x + 15y = -6
15y = -3x - 6
y = (-1/5)x - (2/5)
Now we can graph these two lines and find their point of intersection, which is the solution to the system of equations:
![graph](https://www.mathsisfun.com/algebra/images/graph-2-lines.svg)
The solution is the point (-2, 0.4).
Therefore, the correct graph is **(A)**.
8x - 4y = -16
-4y = -8x - 16
y = 2x + 4
3x + 15y = -6
15y = -3x - 6
y = (-1/5)x - (2/5)
Now we can graph these two lines and find their point of intersection, which is the solution to the system of equations:
![graph](https://www.mathsisfun.com/algebra/images/graph-2-lines.svg)
The solution is the point (-2, 0.4).
Therefore, the correct graph is **(A)**.