The rate charged per hour by each mechanic was: x = 75 $ / hr and y = 115 $ / hr.
<h3>What is a system of equations?</h3>
A system of equations is two or more equations that can be solved to get a unique solution. the power of the equation must be in one degree.
Given;
The first mechanic worked for 20 hours, and the second mechanic worked for 15 hours.
Together they charged a total of $3225.
For this case we have the following variables:
x be the amount of $ / hr that the mechanic obtains 1.
y be the amount of $ / hr obtained by mechanic 2.
An equation to express this would be:
x + y = 190
20x + 15y = 3225
Solving the system of equations we have:
20x + 15(190 -x) = 3225
20x + 2850 - 15x = 3225
5x = 375
x = 75
simililary
y = 190 - x
y = 115
Hence, the rate charged per hour by each mechanic was:
x = 75 $ / hr
y = 115 $ / hr
Learn more about equations here;
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Answer:
C.) 5, 12, 13
Step-by-step explanation:
In a right triangle, the sum of the squares of the two shorter sides must equal the square of the longest side (Pythagoras).
a² + b² = c²
We can test each set of numbers to see which one fits.
A.) 8² + 12² = 16²
64 + 144 = 256
208 ≠ 256
B.) 6² + 7² = 8²
36 + 49 = 64
85 ≠ 64
C.) 5² + 12² = 13²
25 + 144 = 169
169 = 169
The numbers 5, 12, and 13 could represent the lengths of the sides of a right triangle.
D.) 16² + 32² = 36²
256 + 1024 = 1296
1280 ≠ 1296
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.
Area of rectangles = Length x width.
Area of triangles = 1/2 x base x height.
1 face is 12 x 10 = 120 square units
1 face is 12 x 8 = 96 square units
1 face is 12 x 6 = 72 square units
And 2 faces are 1/2 x 8 x 6 = 24 square units
Answers are 24 , 72 and 96 square units.
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