The correct answer is D. 6
Explanation:
To know precisely how the number of restaurants in the city decreases over time, it is necessary to determine the 18% of the total of restaurants each year and to subtract this number. The process year per year is shown below:
First-year- 60 restaurants- Find the percentage by writing the known value and using cross multiplication
%
%


Number of restaurants that were closed
New total
Second-year - 49.2 restaurants- Repeat te process
Shortened version of the equation. Total of restaurants, multiplied by percentage and divided into 100 (total percentage)

New total
Third-year- 40.4 restaurants


New total
Fourth-year- 33.2 restaurants


New total
Fifth-year- 26.9 restaurants


New total
Sixth-year- 22.1 restaurants



According to this at this rate, it will take at least 6 years for the number of restaurants to be below 20.