Answer:
Step-by-step explanation:
Let's check his work by simplifying the given expression.
When I compare Marty's result and this result, they are un-equal. Hence, Marty is incorrect.
Marty's mistake
[tex]\\ \sf\longmapsto 2(x-2)-2(3)[/tex]
[tex]\\ \sf\longmapsto 2x-2(2)-6[/tex]
[tex]\\ \sf\longmapsto 2x-4-6[/tex]
[tex]\\ \sf\longmapsto 2x-10[/tex]
Marty was wrong in opening brackets