Please check my answer, if it isn’t right please correct me >.<

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

Choose the more precise measurement. 26.4 cm or 8.39 cm

Which expression is the factorization of x^2+10+21