Answer:
12.6
Step-by-step explanation:
If 21 divided by 5 is 4.2, you should multiply 3 by 4.2 you'll then get 12.6. to double check, do 5 divided by 3, which is 1.67, and 21 divided by 12.6 is also 1.67. so side OP is 12.6! :)
Answer:
100 girls
Step-by-step explanation:
The ratio of boys : girls is 2 : 5.
In other words, boys are 2 parts of the school while girls are 5 parts of the school.
Since there are 40 boys, 2 parts of the school is 40. Thus:

1 part is 20.
Since there are 5 parts girls, there are

100 girls.
Answer: 100 girls
Area = r^2 x PI
to find r take the square root of the area:
r = √100 = 10
The circumference of a circle is the diameter times PI.
The diameter is 2 times r = 2 x 10 = 20
The circumference = 20PI m
The answer is C.