Answer:
10 km/h
Step-by-step explanation:
Let x km/h be Jamie's running speed. On average, Jamie can bike five times as fast as he can run, then Jamie's biking speed is 5x km/h.
Biking:
Distance = 25 km
Rate = 5x km/h
Time [tex]=\dfrac{25}{5x}[/tex] hours
Running:
Distance = 25 km
Rate = x km/h
Time [tex]=\dfrac{25}{x}[/tex] hours
To travel 25 km, Jamie needs 2 hours more when he is running than when he is biking.
Hence,
[tex]\dfrac{25}{5x}+2=\dfrac{25}{x}\\ \\\dfrac{5}{x}+2=\dfrac{25}{x}\\ \\2=\dfrac{25}{x}-\dfrac{5}{x}\\ \\\dfrac{25-5}{x}=2\\ \\\dfrac{20}{x}=2\\ \\20=2x\\ \\x=10\ km/h[/tex]
