Venissa's mother has an antique button collection. She has seven triangular shaped buttons. She has six solid yellow buttons and three solid blue buttons. She also has six buttons which are square shaped. Her most expensive button is blue/yellow and it is not triangular or square shaped. Of the triangular buttons, two are solid yellow and one is solid blue. Of the square buttons, two are solid blue and three are solid yellow. Besides her most expensive button, she only has another non-triangular/non-square button in her collection and it is yellow. Can you determine how many buttons are in her collection?
For the answer (try not to look right away!).