Why not look up "standard deviation" yourself, to be sure? But yes, the std. dev. is the sqrt of the variance.
Answer:

Step-by-step explanation:
Note that because BD is an angle bisector, then angle XBD and angle DXY are equal. Also note that BYD and BXD are equal because they are both right angles. Also, by the transaitive property, BD = BD. Therefore, it can be concluded that BXD is congruent to BYD.
Therefore, we must solve
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For # 9, the answer is 4 pants and 11 shirts, see in the comments for my explanation
Let's have this equation equal y first. All we have to do is add y to both sides and subtract 4 from both sides.
5x-4=y
Now, to get a parallel line, the y intercept has to change. The y intercept (the -4 in the equation) can be an infinite amount of number but -4.
Let's choose 6. We would have 5x+6=y or you could put it in the way the other equation was, 5x-y=-6.
Answer:
1st:

2nd:

3rd:

Step-by-step explanation:
Graph all of them and see which ones cross the x- axis at the same points.