Answer:
LXXXVII
Step-by-step explanation:
L=50 X=10 V=5 I=1
So basically you need to figure out what adds up to the 87. so use L, or 50. now XXX=30. so now you have 80 so we still have 7 left over, so we can write 7 I's or a 5, (V) and two I's. We should use the V and the I. So we take one V, or 5. and two I's which together is 7. which leads us too LXXXVII. also always remember to have the biggest number first, in this case the L (50).
X = the number of months the tire was used
y = the thickness of the tire tread
y = -(3/7)x + 20
Substitute x for 20 (the number of months the tire was used) and solve for y.
The next question: Substitute x for 49 (the number of months the tire was used) and solve for y.
C, because when you add 45 on both sides, and then after that when you have to subtract 15 in both sides, you get 0 = 120.
from what I know
A=4
B=3
C=2
and a plus adds 0.33 and a minus minuses 0.33
question wants us to find yearly average or average per 1 year
since these grades span over 2 years, we must divide the total average by 2
averagefresh=sum of fresh grades/4 grades per year
averagesoph=sum of soph grades/4 grades per year
yearlyaverage=(averagefresh+averagesoph)/2
freshman:
(C)+(B)+(A)+(C-)=2+3+4+(2-0.33)=10.67
sophomore:
(B+)+(A-)+(C+)+(B-)=(3+0.33)+(4-0.33)+(2+0.33)+(3-0.33)=12
averagefresh=10.67/4=2.6675
averagesoph=12/4=3
yearlyaverage=(2.6675+3)/2=2.83375
so it's about a 
average
