Pls help with this quick

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

Look at triangle wxy what is the length (in centimeters) of the side wy of the triangle?

In the equation sqrt(n+5)-sqrt(11-10)=1. what is the value of n