Answer:

I think this is it?? very sorry if it's incorrect
Speed=6 miles per hour
Distance =9.6 miles
Speed =distance /time
Time=distance/speed=9.6/6=1.6 hours
Symmetric property, I remembered the answer for this for my summer school. This is one of the equivalence properties of equality.
To find the gradient of a line you use this equation: Rise / Run
I am assuming this is a graph where both the x and y-axis increase in value by one.
So first of all, you should draw out this graph.
Second, draw a point at each of the given coordinates.
Now, join these points by drawing a right angle triangle. Put simply, draw a line from the point (4, -7) down until it is on the same level as the point (2, -3), then draw a line across.
Finally, measure the length of both these sides and use them in the equation above.
Let's assume the rise (vertical line) and the run (horizontal line) are 5 and 8 respectively. We can do 5/8 to get a gradient which is 0.625.
Your answer would be $13.50 because is 3 bags cost 6.75 and you need 6 bags then just multiply the 6.75 by 2 and you get your answer :)