Answer:
[tex]\huge\boxed{x=\dfrac{24}{5},\ y=\dfrac{19}{5}}[/tex]
Step-by-step explanation:
[tex]\left\{\begin{array}{ccc}-3y=-3x+3&\text{divide both sides by (-3)}\\-4y=x-20\end{array}\right\\\\\left\{\begin{array}{ccc}y=x-1&(1)\\-4y=x-20&(2)\end{array}\right\\\\\\\text{Substitute (1) to (2):}\\\\-4(x-1)=x-20\qquad\text{use the distributive property}:\ a(b+c)=ab+ac\\\\(-4)(x)+(-4)(-1)=x-20\\\\-4x+4=x-20\qquad\text{subtract 4 from both sides}\\\\-4x=x-24\qquad\text{subtract}\ x\ \text{from both sides}\\\\-5x=-24\qquad\text{divide both sides by (-5)}\\\\x=\dfrac{24}{5}[/tex]
[tex]\text{Put it to (1)}:\\\\y=\dfrac{24}{5}-1\\\\y=\dfrac{24}{5}-\dfrac{5}{5}\\\\y=\dfrac{24-5}{5}\\\\y=\dfrac{19}{5}[/tex]
