Z=Xk228=12kk=228/12k=19Z=18*19Z=342 57=3k57/3=k19=k again Z=8*19Z=152
hope i could help :)
Answer:
Step-by-step explanation:
Let the speed of the car is c and speed of the plane is p.
<h3>We are given:</h3>
The speed of the plane is 7 times the speed of the car
The distance traveled is
The time difference to travel this same distance is 3 hours.
<h3>We know that:</h3>
- d = ts, where d- distance, t- time, s - speed
Find the time for car and plane and their difference.
<h3>Car</h3>
<h3 /><h3>Plane</h3>
- t = d/s = 315/p = 315/(7c) = 35/c
<h3 /><h3>The difference</h3>
<u>Solve it for c:</u>
- (315 - 45)/c = 3
- 270/c = 3
- c = 270/3
- c = 90 km/h
Now find the speed of plane:
As we see, Jenny is right
Answer: A. 85.7
Step-by-step explanation:
Given : Two sections of a class took the same quiz.
Section A had 15 students who had a mean score of 80, and Section B had 20 students who had a mean score of 90.
We know that , 
Then , for section A :


Similarly in Section B, 
Total scores = Sum of scores in sec A+Sum of scores in sec B
=1200+1800=3000
Total students = Students in sec A +Students in sec B
=15+20=35
Now , the mean score for all of the students on the quiz =

Hence, the approximate mean score for all of the students on the quiz = 85.7
Thus , the correct answer is option A. 85.7.
A + b = d+c
<span>a - b = e - c </span>
The b and c cancel out.
<span>2a = d+e </span>
<span>a = (d+e)/2 </span>