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.
[tex]\frac{4}{2} -3[/tex] [divide]
[tex]2-3[/tex] [subtract]
[tex]-1[/tex]
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 [tex]\frac{|measured-exact|}{exact} *100%[/tex]. 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.
[tex]\frac{|75-80|}{80} *100%[/tex] [subtract]
[tex]\frac{|-5|}{80} *100%[/tex] [solve absolue value]
[tex]\frac{5}{80} *100%[/tex] [divide]
[tex]0.0625*100%[/tex] [multiply]
[tex]6.25[/tex]
Since the problem said to round to one decimal place, we know that the answer is 6.3%.
