The diagram below shows a city block and each rectangle represents a different building. The shaded buildings have acceptable fire prevention
systems installed. Recently the city council passed a law mandating that
at least 80% of the buildings in each city block must have acceptable fire
prevention systems installed. Note: Upgrading part of a building does not
count. The entire building must have an acceptable fire prevention system.

a. How many of the buildings with unacceptable fire prevention must be
improved for this block to be in compliance with the new law?

b. This block must have a minimum % increase in buildings with
acceptable fire prevention systems in order to be in compliance with the law.
9:00pm

**Assume that each rectangle in the figure is the same size.