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:
x = 18
Step-by-step explanation:
We need to find the value of x.
We know that the sum of angles of a triangle is equal to 180°. So, using this property,
2x+1+3x-1+90 = 180
2x+3x = 180-90
5x = 90
x = 18
So, the value of x is equal to 18.
28 x 12 = 336
336 - 16 = 320
320 divided by 4 = 80
80
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