Answer: A; 6.3%
Step-by-step explanation:
Problem 1
For the first problem, we first want to find y so that we can plug it into the expression.
We can use elimination method for the system of equations to solve.
3x+3y=21
3x-y=5
We subtract both equations to eliminate x.
4y=16                                        [divide both sides by 4]
y=4
Now that we know y, we can plug it into the expression.
 [divide]
                                         [divide]
 [subtract]
                                         [subtract]

We know that the answer is A.
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Problem 2
For the second problem, we need to know how to calculate percent error. The formula for precent error is  . We know that the exact value is 80 because the buyer was supposed to given 80. 75 is the measured value because that was what the buyer was given.
. We know that the exact value is 80 because the buyer was supposed to given 80. 75 is the measured value because that was what the buyer was given.
 [subtract]
                               [subtract]
 [solve absolue value]
                                   [solve absolue value]
 [divide]
                                     [divide]
 [multiply]
                               [multiply]

Since the problem said to round to one decimal place, we know that the answer is 6.3%.
 
        
             
        
        
        
Answer:
13.75
Step-by-step explanation:
65 - 10 =55
55 ÷ 4 = 13.75
 
        
             
        
        
        
Answer:
$15 per hour
Step-by-step explanation:
30 hours per week x 52 weeks in a year = 1560 hours per year
23,400 / 1560 = $15 per hour
 
        
             
        
        
        
Answer:
What is exactly the question?
 
        
             
        
        
        
Answer:
car a, car b
Step-by-step explanation:
 car a 2x + 2= 4x
car b 3x + 3= 9x
both cars 13x