It’s prime because none of the other answers work.
Id there are 21 girls according to my calculations there would be a heap amount of boys which is 23
After having done this on paper:

We want to isolate the variable, and the first step is to subtract the 8.

Since the <em>n</em> is being multiplied by 3, and that = 8, we can multiply both sides by 3.
<em>n</em> = 24
Let me know if this helped you understand better.
Also, you can check this by substituting in 24 for <em>n</em>.
Answer:
a = 49°
Step-by-step explanation:
OB = OC ( both radii of the circle ), thus
Δ BOC is isosceles and the base angles are congruent, that is
∠ OBC = ∠ OCB = 41° , so
∠ BOC = 180° - (2 × 41)° = 180° - 82° = 98°
The angle on the circumference BAC is half the angle at the centre for angles subtended on the same arc , thus
a = 0.5 × 98° = 49°