[tex] \left \{ {{-3x-3y=3\:(I)} \atop {y=-5x-17\:(II)}} \right. [/tex]
Replace the equation y in the first equation.
[tex]-3x-3y=3 (I)[/tex]
[tex]-3x-3*(-5x-17)=3[/tex]
[tex]-3x+15x+51=3[/tex]
Now, put the numbers with letter (incognito) to the right and numbers without letter to the left, changing the signal when changing sides.
[tex]-3x+15x=3-51[/tex]
[tex]12x = -48[/tex]
[tex]x = \frac{-48}{12} [/tex]
[tex]\boxed{\boxed{x = - 4}}\end{array}}\qquad\quad\checkmark[/tex]
Now substitute the found value "x" in the equation y (second equation):
[tex]y=-5x-17\:(II)[/tex]
[tex]y = - 5*(-4) - 17[/tex]
[tex]y = 20 - 17[/tex]
[tex]\boxed{\boxed{y=3}}\end{array}}\qquad\quad\checkmark[/tex]
Answer:
[tex]\underline{\textbf{The\:values\\:found\:are:\:X = -4\:and\:
Y = 3} }
[/tex]