Answer: The slope of the line is 
Step-by-step explanation:
The slope of a line can be calculated with the following formula:

Then, given the points
and
, you can identify that:

Knowing these values you can substitute them into the formula for calculate the slope:

Finally, evaluating, you get that the slope of that line is:

You might have made an error the first time you solved for x. I got x = -0.5.
When you have your log base 4, the way you cancel that out is by making 4 the base on both sides, so you get 4^(log4) to reduce to 1, and you're left with:
2x + 3 = 4^(1/2) ... Simplify
2x + 3 = 2
2x = -1
x = -1/2
If you plug that back in, everything checks out. Maybe double check your use of logarithm/exponent properties?
Answer:
because it has a weak inter molecular forces between its layers
Yes -4 is a interference number