Final answer:
By solving the second equation for y and substituting into the first, we find the solution to the system of equations: x = -4.5 and y = -20.5.
Step-by-step explanation:
To solve the system of equations by substitution, we need to isolate one variable in one of the equations and then substitute it into the other equation. Let's take the second equation, 3x = y + 7, and solve for y. This gives us y = 3x - 7.
Now we substitute this expression for y into the first equation, 8x = 2y + 5, which gives us:
8x = 2(3x - 7) + 5
Simplify and solve for x:
8x = 6x - 14 + 5
8x - 6x = -14 + 5
2x = -9
x = -4.5
Next, we substitute x back into the equation y = 3x - 7 to find y:
y = 3(-4.5) - 7
y = -13.5 - 7
y = -20.5
The solution to the system of equations is x = -4.5 and y = -20.5.