Instruction
Great job! Let's now calculate something more interesting!
Exercise
The mayor of San Francisco has decided to renovate all bicycle routes in the Downtown district (stored in sf_chains with id = 90). Calculate the total cost of all renovations, given the following costs:
- 250 USD per 1 kilometer of bicycle routes,
- an additional 100 USD for each bicycle route (for new signs).
Name this column total_price.



