Correct probability : 3/7
To find the correct probability, Noura needs to count ALL of the times she tossed the coin. To find that we just add 15 + 20, which equals 35.
Then to calculate the probability she will get heads is out the number of heads landed over the amount of times the coin was flipped.
15/35
We then simplify this fraction by dividing the top and bottom both by 5.
This leaves us with the answer of 3/7.
When a line is given in the form

The slope of the line is m. So, in this case, the slope of
is 1.
Given a slope
, you find the slope of a perpendicular line
by imposing

So, if the given line has slope 1, a perpendicular line has slope
given by

and thus 
So, we want a line with slope -1 and passing through (12,-1). Using the fomula

we get

You awnser would be B- (-4,-4) :)