18. Lombard Street in San Francisco, California, is paved with red bricks and is a switchback road with a speed limit of 8 km/h because of its extreme grade. The angle of elevation of Lombard Street in one section reaches 15. Determine the grade of this section of road to the nearest percent. Height (cm) STO Thinkstock 9. A hill on Oak Street has an angle of elevation of 11. A hill on Broadway Street has a 21% grade. Which hill is steeper? (Hint: Convert both into slope)