Answer:

Step-by-step explanation:
Coordinates of Point b
b lies on the circle whose equation is 

Comparing with the general form a circle with center at the origin: 
The radius of the circle =17 which is the length of the hypotenuse of the terminal ray through point b.
For an angle drawn in standard position through point b,
x=-8 which is negative
y=15 which is positive
Therefore, the angle is in Quadrant II.

Answer:4
Step-by-step explanation:
First, factor out 5:
5 (x² -x -20)
We need two numbers that add to -1 and multiply to -20. -5 and 4 satisfy this.
5(x-5)(x+4)
Answer:
Step-by-step explanation:
x = father's age
y = son's age
Nowadays:
3x = y
5 years ago:
4(x - 5) = y - 5
4x - 20 = y - 5
4x = y + 15
I hope I've helped you.
Answer:
40 classrooms
Step-by-step explanation:
Divide 1200 by 30.
1200÷30=40
If 390 students are boys just subtract 390 from 1200.
1200-390= 810
There must be 810 girls if there are 390 boys