If n(A) = p, n(B) = q and n(A∪B) = r, find n(A∩B) in terms of p, q and r. ?

Diana is painting statues she has 7/8 of a liter of paint each statue requires 1/20 of a liter of paint how many statues can she paint?

If there are 3.281 feet in 1 meter, how many inches are in one centimeter

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document