How many vertices does this shape have?

Hi, can anyone show me how to do this problem? 100 points for this. in advance

The difference between two numbers is one. three times the larger number minus two times the smaller number is 9. what are the two numbers

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of