Answer= 71.0874524715 that is the answer but you will have to shorten it
B(x) = 100 - 3.5x
84 = 100 - 3.5x
3.5x = 100 - 84 = 16
x = 16/3.5 = 4.6 kilometers
96 = 100 - 3.5x
3.5x = 100 - 96 = 4
x = 4/3.5 = 1.1 kilometers
Therefore, the boiling point of water is between 84°C and 96°C at elevations of between 4.6 kilometers and 1.1 kilometers.
Here is the solution for the eqns.
(-2,4), (2,5)
Slope equation : (y₂-y₁) / (x₂-x₁)
Plug in the values.
m = slope
m = (5-4) / (2 + 2)
Simplify.
m = 1/4
So, your slope is 1/4
~Hope I helped!~