Answer:
Step-by-step explanation:
To properly apply the substitution method, it will be better for us to rearrange the system of equations to have similar variables on the same side
We can simply evaluate equation 1 to have
y = -20
From the first equation alone, we can evaluate the value of y as -20. This is because only one unknown is present in equation one, hence a single equation is sufficient enough to evaluate it. If to unknowns were present, the two equations would have been utilized to evaluate the solution.