Final answer:
The value of x in the solution to this system of equations is 4.
Step-by-step explanation:
To find the value of x in the solution to this system of equations, we need to solve the system of equations by substitution or elimination. Let's use the substitution method:
First, we can substitute the value of y from the second equation into the first equation:
5x - 5(-7x + 8) = 120
Simplifying this equation gives us:
5x + 35x - 40 = 120
Combining like terms:
40x - 40 = 120
Adding 40 to both sides:
40x = 160
Dividing both sides by 40:
x = 4
Therefore, the value of x in the solution to this system of equations is 4.