First you can solve for b: Subtract a on both sides and get 2b=-a+10, then divide by 2 to get b by itself and get: b=-1/2a+5
Then you can plug in this equation for b in the other: This would give you: 2a+-1/2a+5=6. Then you can use that equation to solve for a and get: 1.5a+5=6, subtract 5, 1.5a=1, divide by 1.5, a=1/1.5
Then you can plug in the value of a to solve for b.
Considering the situation described, we have that:
- The appropriate null hypotheses is
.
- The appropriate alternative hypotheses is
.
<h3>What are the hypotheses tested?</h3>
At the null hypotheses, it is tested if the mean has not been reduced, that is, it still is of 5.2 hours, hence:
.
At the alternative hypothesis, it is tested if the mean has been reduced, that is, it is now of less than 5.2 hours, hence:

More can be learned about hypotheses tests at brainly.com/question/26454209
Answer:
Please mark as brainliest.
-8 and -9 because it is negative
You can use elimination to solve systems of equations with 3 equations. I know how to solve systems of equatons with 3 equations, but I use a different process, I don't know how to use the elimination method.