Example

Finding Flat and Uphill Biking Speeds Using a Known Total Distance

Apply the distance, rate, and time problem-solving strategy to find two unknown uniform speeds for consecutive trip segments when the segment distances add up to a known total.

Problem: Phuong left home on his bicycle at 10:00. He rode on the flat street until 11:15, then rode uphill until 11:45. He rode a total of 3131 miles. His speed riding uphill was 0.60.6 times his speed on the flat street. Find his speed biking uphill and on the flat street.

  1. Read and draw: Sketch the route from home with two segments: flat street (10:00 to 11:15) and uphill (11:15 to 11:45). The total distance is 3131 miles. Create a rate–time–distance table.
  2. Identify: Phuong's biking speed on the flat street and his biking speed uphill.
  3. Name: Let rr = the speed on the flat street in mph. Because his uphill speed was 0.60.6 times as fast, it equals 0.6r0.6r. Convert the clock times to elapsed times: riding on the flat street lasts from 10:00 to 11:15, which is 1.251.25 hours; riding uphill lasts from 11:15 to 11:45, which is 0.50.5 hours. Multiply rate by time to fill in the distance column:
Rate (mph)Time (hrs)Distance (miles)
Flatrr1.251.251.25r1.25r
Uphill0.6r0.6r0.50.50.5(0.6r)0.5(0.6r)
Total3131
  1. Translate: The flat distance plus the uphill distance equals the total of 3131 miles: 1.25r+0.5(0.6r)=311.25r + 0.5(0.6r) = 31
  2. Solve: Multiply 0.50.6=0.30.5 \cdot 0.6 = 0.3: 1.25r+0.3r=311.25r + 0.3r = 31 Combine like terms: 1.55r=311.55r = 31. Divide both sides by 1.551.55: r=20r = 20 The speed on the flat street is 2020 mph. The uphill speed is 0.620=120.6 \cdot 20 = 12 mph.
  3. Check: Flat street: 201.25=2520 \cdot 1.25 = 25 miles. Uphill: 120.5=612 \cdot 0.5 = 6 miles. Total distance: 25+6=3125 + 6 = 31 miles. \checkmark
  4. Answer: Phuong's speed biking on the flat street was 2020 mph and his speed biking uphill was 1212 mph.

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Updated 2026-05-02

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