Please help me... thank you <3

There are 20 children in the cast of a class play and 8 of the children are boys of the boys 4 have a speaking part in the play and of the girls 8 do not have a speaking part in the play if a child from the cast of the place chosen at random what is the probability that the child has a speaking part

What is a possible solutions of the x> 3?

How much dextrose 70% must be mixed with dextrose 5% to prepare 1,000 ml of dextrose 20%?