A runner's racecourse has a total distance of 5 mi . Race officials want to mark the course every 550 yd with a flag, including one at the finish line. (The starting line does not need a flag.) How many flags are needed? First fill in the blanks on the left side of the equation using three of the ratios shown. Then write your answer on the right side of the equation.

To solve this problem, let's first convert the total distance of the racecourse from miles to yards, since the flags will be placed every 550 yards. 1 mile = 1,760 yards, therefore: 5 miles = 5 × 1,760 yards = 8,800 yards. Now, we want to find out how many flags are needed. We will place a flag every 550 yards, starting from the first flag at the 550-yard mark up to the finish line at 8,800 yards. Now, we can do the calculation: 8,800 yards (total distance) ÷ 550 yards (distance between flags) = 16 flags. However, there is a flag at the finish line, so we count flags at every interval including the last one. The equation will look like this: 8,800 yd = (550 yd × 16) flags + 1 flag at the finish line. Therefore, the total number of flags needed is **16**.