I'm guessing D, but no so sure.
Assuming you want the equation in slope intercept form, you first need to use slope formula to find the slope.

Plug in the coordinates that you have, (3,-1) and (4,7), for the x and y values respectively.

Which reduces to 8/1=8.
The slope of your equation is 8.
Slope intercept form is: y=mx+b. m is your slope and b is your y-intercept, x and y stay unchanged.
Plug the slope in:
y=8x+b.
Now, you can plug one of the sets of coordinates into the x and y of the equation to find b. I'm using (3,-1).
-1=8(3)+b
-1=24+b
Subtract 24 from both sides.
-25=b
Now plug this into the equation!
y=8x-25 is your final equation.
I hope this helps :)
Answer:
In all you have 800 students.
The ratio of girls to boys is 300:500
500 x 300 = 150000
Step-by-step explanation:
Hope this helps?
12.70 or rounded 13 yeeeeeeeeee boiiiiiiiiiiii