If a cirlce is 360* the cloest answer would have to be.... *c*
Step-by-step explanation:
1) -9 = 9 true/false
the answer is false because negative and positive quite unlike in terms.
2) -(-21) = -21
Using the symbols multiplication rule,
Where,
<h2>
+ × + = +</h2><h2>
- × - = +</h2><h2>
- × + = -</h2><h2>
+ × - = -</h2>
Therefore, -(-21) = +21 = 21
⟼ 21 = -21 
Answer:
Your friend is incorrect because if you divide 21 by 7 you will get 3 if you add 7 to 3 you get 10 therefore your friend is incorrect.