Answer:

Step-by-step explanation:
![\displaystyle -9[5] + 3[7] + 4 = -45 + 21 + 4 = -20](https://tex.z-dn.net/?f=%5Cdisplaystyle%20-9%5B5%5D%20%2B%203%5B7%5D%20%2B%204%20%3D%20-45%20%2B%2021%20%2B%204%20%3D%20-20)
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25% because 21 is a quarter of 84. And 21 times 4= 84, so 21 is 25% of 84.
Answer:
B)
Step-by-step explanation:
Square <span>polygon is always regular, other have some scenarios which makes them regular but they are not always regular.</span>
Answer:
495 combinations of 4 students can be selected.
Step-by-step explanation:
The order of the students in the sample is not important. So we use the combinations formula to solve this question.
Combinations formula:
is the number of different combinations of x objects from a set of n elements, given by the following formula.

How many combination of random samples of 4 students can be selected?
4 from a set of 12. So

495 combinations of 4 students can be selected.