9)
8x+4*6
8x+24
11)
3t+2c=6tc
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:
arc = 25.29
Step-by-step explanation:
first find the circumference:
C = 2r(Pi) = 2(10)(3.14) = 62.8
since subtended, then we're looking for these opposite angle of 215 degrees:
360 - 215 = 145 degrees
62.8/360 = 0.1744 per degree
0.1744 x 145 = 25.29
Factor because the answer to a multiplication problem is a factor.
The answer is not in standard form is the second one and in standard for is the second one hole this helps