It's C because you need to find how many points each student earned per grade (freshman & sophomore). Then you multiply it by 30 to find out how many points each student scored in the whole class.
Hope this helps!
Answer:
100%=25
Step-by-step explanation:
B. Multiply the top equation by 3
-2y will turn into -6y and the y's will cancel out
Answer:
f=24km/h
Step-by-step explanation:
Alright, here's what we know.
He travels 2 hours at a fast speed, lets call that speed f km/h
He then travels 3 hours at (f-10) km/h
In these 5 hours, he travels 90km
So we have the formula velocity = distance/time. If you don't know where that formula comes from, let me know and I'll explain.
So we have:

d and t are given to us as 90 and 5 respectively
v is going to be his average speed, so we take 2 times the fast speed plus 3 times the slower speed and divide it by 5. This gives us the average speed he traveled over the 5 hours.

2f+3f−30=90 by cancelling the 5's in the denominator and expanding 3(f−10)
5f=120
f=24km/h
So his faster speed is 24 km/h. Let me know if this solution did not make sense to you at any point.