This are similar answers to your questions.
Answer:
D.
Step-by-step explanation:
it should be the sales tax because you pay a little bit more.
Answer: plot a point at (-8, -5)
The y coordinate flips from positive to negative, or vice versa, when we reflect over the horizontal x axis. The x coordinate stays the same.
The rule can be written as 
30%,
1-5=20%
so 50%-20%= 30%