How do you use the quadratic formula

Which one is the correct answer, and why?

The statements below can be used to prove that the triangles are similar. ? △abc ~ △xyz by the sss similarity theorem. which mathematical statement is missing? ∠b ≅ ∠y ∠b ≅ ∠z

Afew weeks ago, vera bought 5 apples from her local farmers' market. today, she bought 4 apples. what is the percent of decrease in the number of apples bought?