Question 1079957
b is easier
It is inverse variation because as y increases, x decreases or vice versa.
y=k/x.  Find k. Use 100=k/0.5; k=50; check in other two 20=k/2.5=50/2.5, check; 5=k/10=50/10 checks.
y=50/x
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a.  As x goes from -10 to 50, y goes from 0.8 to -4, there is a direct variation with what looks like a factor of -5
y=kx
-4=50k
k=-4/50=-2/25
y=-0.08/x
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check in other two.
0.8=(-2/25)(-10)=20/25, checks
0.16=(-2/25)(-2), checks.