Answer:
a=12
Step-by-step explanation:

90/15=6x4=24 Riley would on average score 24 points.
Answer:
6 weeks
Step-by-step explanation:
Set up a proportion where x is the amount of time with 12 pupils:
= 
Cross multiply and solve for x:
4x = 24
x = 6
So, it will take 12 pupils 6 weeks to complete the job.
D: NP=1.25, because the ratio of 8/2 is equal to 5/X.
0.25=y. Need an explanation?