An algebra problem by Victor Paes Plinio
Jane want to clear you garage and search for old things. She find an part of the old stamp collection from his grampa. In the first part of the book have the 50 cents and 1dollar stamps. In the front of the book have this riddle:
"In here only have 50 cents and 1 dollar stamps. For make this part of my collection, I spent 100 dollars with 160 stamps. What is the number of 1 dollar stamps?"
sorry, I forget to put a title.