Can someone help me pls

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 two criteria are needed for triangles to be similar

100 points, hi, i’m not sure how to get the equation from the graph and table.