Answer :
[tex]7-3(5t-10)=67[/tex]
[tex]7-(3*5t-3*10)=67[/tex]
[tex]7-15t-(-30)=67[/tex]
[tex]7-15t+30=67[/tex]
[tex]-15t=67-30-7[/tex]
[tex]-15t=30[/tex]
then...
[tex]t=-\frac{30}{15}[/tex]
[tex]\boxed{\boxed{t=-2}}[/tex]
[tex]7-(3*5t-3*10)=67[/tex]
[tex]7-15t-(-30)=67[/tex]
[tex]7-15t+30=67[/tex]
[tex]-15t=67-30-7[/tex]
[tex]-15t=30[/tex]
then...
[tex]t=-\frac{30}{15}[/tex]
[tex]\boxed{\boxed{t=-2}}[/tex]