If the slope is 5 perpendicular would be -1/5 just flip the slope around
For b it's 39 because you multiply 5 and 7 giving you 35 then add 4 Wich equals 39. I might be incorrect. check it out.
I want to say about 27% but I am not completely sure
Both are 1/2 because there is two sides so half the time it would be heads and half would be tails
