Solve the system by the method of your choice.
\[
\left\{\begin{array}{l}
y=-2 x-5 \\
-8 x-20=4 y
\end{array}\right.
\]
Select the correct choice below and, if necessary, fill in the answer box to complete your choice.
A. The solution set is (Type an ordered pair.)
B. There are infinitely many solutions. The solution set is $\{(x, y))\}$. (Simplify your answer. Type an equation.)
C. There is no solution. The solution set is $\varnothing$.
Answer
Thus, there are infinitely many solutions, and the solution set is $\{(x, -2x-5)\}$ for all real numbers $x$.
Step 1 ：We can find $x$ by substituting the first equation into the second. From $-8x-20=4(-2x-5)$, we get $-8x-20=-8x-20$, which simplifies to $0=0$.
Step 2 ：This means that the two equations are equivalent, and any value of $x$ will satisfy both equations.
Step 3 ：To find $y$, we can substitute any value of $x$ into the first equation. For example, if $x=0$, then $y=-2(0)-5=-5$.
Step 4 ：Thus, there are infinitely many solutions, and the solution set is $\{(x, -2x-5)\}$ for all real numbers $x$.
