Answer: 
Step-by-step explanation:
Given a System of linear equations, the solution of the system is the point
in which the lines intersect, where "x" is the x-coordinate and "y" is the y-coordinate.
Having the following System of equations:

You can use the Elimination method to find the value of "x":
-Multiply the second equation by 3.
- Add the equations.
- Solve for "x".
Then, you get:

Answer:
F=−4c 2 +7c+5
Step-by-step explanation:
Answer: 21points
Step-by-step explanation: 3 times 7 equals 21