Discover Math Matters! With over 15 million books sold worldwide, this award-winning series of easy-to-read books will help young readers ages 5-8 approach math with enthusiasm. Great for fans of MathStart or Step into Reading Math. Ruby and her two best friends are excited about going to the amusement park. That is, until they discover that the rides they want to go on have seats for two, not three. Someone will have to ride alone--or...