We are given with an 18 student class that is working a project worked by pairs. Each pair works on a project. In this case, there are 9 teams of 2 individuals working on a single project. Hence for a year or school year, there are 9 projects accomplished each time.
Answer:

Step-by-step explanation:
For this case in order to select the one admiral, captain and commander, all different. We are assuming that the order in the selection no matter, so we can begin selecting an admiral then a captain and then a commander.
So we have 10C1 ways to select one admiral since we want just one
Now we have remaining 9 people and we have 9C1 ways to select a captain since we want a captain different from the admiral selected first
Now we have remaining 8 people and we have 8C1 ways to select a commander since we want a commander different from the captain selected secondly.
The term nCx (combinatory) is defined as:

And by properties 
So then the number of possible way are:

If we select first the captain then the commander and finally the admiral we have tha same way of select 
For all the possible selection orders always we will see that we have 720 to select.
Answer:
3 x^3 y^4 sqrt(5x)
Step-by-step explanation:
sqrt(45x^7y^8)
We know that sqrt(ab) = sqrt(a)sqrt(b)
sqrt(45)sqrt(x^7) sqrt(y^8)
sqrt(9*5) sqrt(x^2 *x^2 * x^2* x) sqrt(y^2 *y^2 *y^2 *y^2)
We know that sqrt(ab) = sqrt(a)sqrt(b)
sqrt(9)sqrt(5) sqrt(x^2)sqrt(x^2) sqrt(x^2) sqrt(x) sqrt(y^2)sqrt(y^2)sqrt(y^2)sqrt(y^2)
3 sqrt(5) x*x*x sqrt(x) y*y*y*y
3 x^3 y^4 sqrt(5)sqrt(x)
3 x^3 y^4 sqrt(5x)
Answer:
Ratios of money made by Jackie and Liana = 
Step-by-step explanation:
We have given,
On selling a lemonade :
Money made by Jackie = $24
Money made by Liana = $36
We need to find the ratios of money made by Jackie and Liana by selling lemonade.
So, Ratio = Money made by Jackie / Money made by Liana
or , Ratio = 
or, Ratio = 
So, the ratios of money made by Jackie and Liana is 