Answer:
-3906
Step-by-step explanation:
-6[7-(-225+15)×3]
Solve everything in the parenthesis first:
-225+15=-210
-6[7-(-210)×3]
Simplify expression:
-6[7+210×3]
7+210=217
-6[217×3]
217×3=651
-6[651]
-6×651=-3906
