I think the answer 3\8( i do not know if its right or not)
The regression line equation is

, the value of the slope is shown as constant 16 and it's a positive constant, hence the correlation between the amount of gas used and degree of the days is a POSITIVE correlation.
If you mean log, then 1.556303
-3/2
slope = rise/run
We can use the two points to calculate rise (y value change) and run (x value change)
slope = (-6)/4 = -3/2