How do u solve number 4? ( it's a cube)

Anyone? 15m is what percent of 60m; 3m; 30m; 1.5 km?

Non-euclidean geometry was discovered when, in seeking cleaner alternatives to the fifth postulate, it was found that the negation could also be true a. true b.false

1. if events a and b are non-overlapping events, how do you find the probability that one or the other occurs? 2. what does it mean if p(a or b) equals 1?