Answer:
1
Explanation:
First, solve four your last bracket, 2 squared is 4 and minus 5 is -1 times 21 is -21. Yet because the outer symbol is a negative, all signs change-making 21 positive. Solve 4*-6, and you get -24. This leaves you with [2-24-4+21] that gives you -5. Yet, because the outer sympol is a negative, 5 becomes positive. This leaves you with 1.