Answer:
Step-by-step explanation:
A function maps an x-value to a single y-value. The graph of the parabola on the left does that.
The table on the right maps -1 to both 10 and 20, so does not meet the definition of a function.
Answer:

Step-by-step explanation:
y-0.8x=0.5
y*10-0.8x*10=0.5*10
10y-8x=5
10y-8x+8x=5+8x
10y/10=5/10+8x/10
y=5+8x/10
5*5+8x/10-2.5
8x+5/2-2.5=4x
y=5+8x/10, x=x
The first one is the one that doesn’t represent a function
Ummm what is the question here