Someone plz answer these questions fast. i want to get them done.(ignore what i wrote)

i'll give a branliest with 5 stars and a u!

If private savings 'v' = 0.75s and total savings 's' equals $4.20 billion, solve for public and private savings.

Which of the following circles have their centers on the x-axis? check all that apply.

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?