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 play is chosen at random, what is the probability that the child has a speaking part?

Probablity is (desired outcomes) divided by (total possible outcomes) or (d)/(t)
 20 total
 8 boys
 girls=20-8-12
 4 boys have speaking parts
8 out of 12 girls do not have speaking part so 12-8=4 girls do have a speaking part
 4 boys and 4 girls have speaking parts
 4+4=8
 8 speaking parts total 20 total people so
 desired outcomes=8
 total possible=20
 8/20=4/10=2/5
 probability is 2/5

Subtracting is the opposite of adding