Answer:
The answer is second one (-2)
Gradient=rise/run=y2-y1/x2-x1
= 7-3(4)/-4--4(0)
As you can't divide by zero the line's equation is x=-4 so it doesn't have a gradient as such. However, a parallel line would be the y-axis
You multiply 75 by 0.8 because that is the percentage of the price you pay after 20% is taken
final answer is $60
