1) y/z for y =-6 z = -20

i got:
-6/-20 = 0.3

2) 2y/-z y= -5 z = -12
i got:
2(-5)/-12 = -10/-12 = 0.83

3) y + z/2z y= -4 z = 8
i got:
-4 +8 / 2(8) = 4/16 = 1/4

4)
-2y + 1/-10 y= 3 z = 10
i got:
-2(3) + 1/-10 = -5/-10 = 0.5

are these correct?

#2 has -z in the bottom

2(-5)/-(-12) = -.83

#3 and #4 really should have parentheses to make it clear that the entire expression is in the numerator. Normally, division is done before addition.

1 + 2/3 = 5/3, but (1+2)/3 = 1
...

That said, your work on #3 and #4 looks good.

ok thanks

5/8_1/2

Let's go through each calculation to verify if they are correct:

1) y/z for y = -6, z = -20:
The formula is y/z. Substituting the given values, we have -6/-20, which simplifies to 0.3.
Your answer is correct.

2) 2y/-z for y = -5, z = -12:
The formula is 2y/-z. Substituting the given values, we have 2(-5)/-12, which simplifies to -10/-12.
However, you made an error in simplifying -10/-12. The correct answer is -10/-12 = 5/6, not 0.83.

3) y + z/2z for y = -4, z = 8:
The formula is y + z/2z. Substituting the given values, we get -4 + 8/2(8), which simplifies to -4 + 1/4.
However, you made an error in simplifying this expression. The correct answer is -4 + 1/4 = -15/4, not 1/4.

4) -2y + 1/-10 for y = 3, z = 10:
The formula is -2y + 1/-10. Substituting the given values, we get -2(3) + 1/-10, which simplifies to -6 + 1/-10.
However, you made an error in simplifying this expression. The correct answer is -6 + 1/-10 = -61/10, not 0.5.

To summarize:
1) Correct: y/z = 0.3
2) Incorrect: 2y/-z = 5/6, not 0.83
3) Incorrect: y + z/2z = -15/4, not 1/4
4) Incorrect: -2y + 1/-10 = -61/10, not 0.5

I hope this clears things up. If you have any further questions, feel free to ask!