First, we need to find the value of y, using the equation given
[tex]-8\mleft(y-10\mright)=160[/tex]then we need to simplify
[tex]-8y+80=160[/tex]we sum like terms
[tex]-8y=160-80[/tex][tex]-8y=80[/tex]then we isolate the y
[tex]y=\frac{80}{-8}[/tex][tex]y=-10[/tex]then for the value of 3y, we substitute the y=-10
[tex]3\mleft(-10\mright)=-30[/tex]