What much is 1/2 - 1/4

Aparallel system functions whenever at least one of its components works. consider a parallel system of n components, and suppose each component works independently with probability 0.5. find the conditional probability that component n works given that the system is working

Which of the functions below could have created this graph?

What is the slope of the line that passes through the points (–9, 2) and (0, 4)? the slope of the line is