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?

3 answers

#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