Ineed with all these problems and need to know is the ones i did correct

Brook states that the distance on the line is 4 units. caleb states that the whole line does not have a distance because it continues on forever. vivian states that the line is 6 units long. which distance did brook measure? which distance did vivian measure?

Whats are the trickiest steps to do when adding or subtracting rational expressions? how does knowledge of rational numbers u in adding and subtracting rational expressions?

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)