<span>3x + y = 9 (I)
</span><span>y = –4x + 10 (II)
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Pass the incognito "4x" to the first term, changing the signal when changing sides.
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simplify by (-1)
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</span></span><span>Substitute in equation (I) to find the value of "Y".
</span>3x + y = 9 (I)
3*(1) + y = 9
3 + y = 9
y = 9 - 3

Answer:

1. y₁ = 70x
2. y₂ = 55x
Solve y₁ - y₂ for x = 11.
Answer:
The z-score for SAT exam of junior is much small than his ACT score. This means he performed well in his ACT exam and performed poor in his SAT exam.
Step-by-step explanation:
Mean SAT scores = 1026
Standard Deviation = 209
Mean ACT score = 20.8
Standard Deviation = 4.8
We are given SAT and ACT scores of a student and we have to compare them. We cannot compare them directly so we have to Normalize them i.e. convert them into such a form that we can compare the numbers in a meaningful manner. The best way out is to convert both the values into their equivalent z-scores and then do the comparison. Comparison of equivalent z-scores will tell us which score is higher and which is lower.
The formula to calculate the z-score is:

Here, μ is the mean and σ is the standard deviation. x is the value we want to convert to z score.
z-score for junior scoring 860 in SAT exam will be:

z-score for junior scoring 16 in ACT exam will be:

The z-score for SAT exam of junior is much small than his ACT score. This means he performed well in his ACT exam and performed poor in his SAT exam.
3 times (2x + 5) is 6x + 15.
6x + 15 = 9 + 3x.
Group by like terms. 6 = -3x
Divide to get x by itself. 6/-3 = -2
Thus -2 = x
Tan(A) = Opp/Adj = CB / AC = 12/9 = 4/3
hope it helps