give explanation

The consumer price index for Planet Econ consists of only two items: books and burgers. In 2015, the base year, the typical consumer purchased 10 books for $25 each and 25 burgers for $2 each. In 2017, the typical consumer purchased 15 books for $30 each and 30 burgers for $3 each. The consumer price index for 2017 on Planet Econ equals: Select one: a. 1.15 b. 1.45 c. 1.25 d. 1.00 e. 1.17 The correct answer is: 1.25