How do you do Algebra? Any Formula?

The sum of the abscissa and the ordinate is six

Achild has a box full of colored building blocks. she will choose one block without looking. the odds against choosing a blue block are 4/7. what is the probability of choosing a blue block? amanda is playing a role-playing game with her friends. she will roll dice to determine if her character unlocks a treasure chest. the probability of her character unlocking the treasure chest is 13/20. find the odds in favor of her character unlocking the treasure chest.

This venn diagram shows the pizza topping preferences for 9 students