Divide 12 by 1.5 so you have a number you can directly multiple with 40.
12/1.5 = 8
The multiple 8 by 40 to get the number of miles.
8(40) = 320
It's the bottom on the right
For a given function, slope is defined as the change in outputs, or y-values divided by the change in inputs, or x-values. In essence the slope asks "For a given change in x, how much does y change?" or even more simply: "How steep is the graph of this function?". This can be represented mathematically by the formula:

Since we have a table of x,y pairs it's the last form of that equation that will be the most useful to us. To compute the slope we can use any two pairs, say the first two, and plug them into our formula:

We can check this answer by using a different pair, say the last two:

.
As a common sense check: Our y-values get smaller as our x-values get bigger so a negative slope makes sense.
m=-3
This is true, because there is an infinite amount of real numbers in both, and they are both countably infinite (so these infinities are equal). Hope this helps!
U use y=mx+b to find the slope, and the answer would be m=-3