Given:
The table of values is
Number of Students : 7 14 21 28
Number of Textbooks : 35 70 105 140
To find:
The rate of change and showing that the ratios of the two quantities are proportional and equivalent to the unit rate.
Solution:
The ratio of number of textbooks to number of students are




All the ratios of the two quantities are proportional and equivalent to the unit rate.
Let y be the number of textbooks and x be the number of students, then

Here, k=5.


Hence the rate of change is constant that is 5.
Answer:
If Ted can clear a football field of debris in 3 hours, in one hour they will have cleared 1/3 of it.
If Jacob can clear a football field of debris in 2 hours, in one hour they will have cleared 1/2 of it.
So if they work together, they will clear 1/2 + 1/3, which is 5/6, in one hour.
So the equation we get is 5/6*x = 1 and if we divide both sides by 5/6 we get that x = 1.2 hours
There are 48 possible outcomes in this situation, and of those outcomes, the ones whose sums are a multiple of three are;
12, 21, 15, 51, 24, 42, 33, 18, 27, 36, 63, 45, 54, 48, 57, and 66. So, that is 16 out of 48 possibilities, or 16/48, which simplifies to 1/3. Written as a percent, the probability of getting numbers whose sum is a multiple of three is 33.33%.
Hope this is helpful! :)
Answer:

Step-by-step explanation:
Let r represent speed in the carpool.
We have been given that on the way to work Juan carpools with a fellow co-worker then takes the city bus back home in the evening. The average speed of the 20-mile trip is 5 miles per hour faster in the carpool.
We know that time is equal to distance over speed.
The total distance is 20 mile. Time taken to travel 20 miles using carpool would be 
The speed on the bus is 5 miles greater, so it will be
. Time taken to travel 20 miles using bus would be 
Total time will be equal to sum of both times that is:

Let us simplify our expression.


Combine numerator:


Therefore, our required expression would be
.