1/4+(x- 1)/m = x/4-( 10-5)/60
x/4=x/m+9/60
The solution is m = 60/11km/h.
Another solution that students can understand is:
Taking off the watch is slow 10 minutes, which means it is late 10 minutes. If you continue to walk at the original speed, you will be (10-5) minutes late, and you will arrive at school on time for the second run, which means that running takes (10-5) minutes less than walking. If you run from home, it's 9 minutes less than walking. So it takes [9-(1 0-5)] minutes less than walking1km. therefore
Walking 1 km needs1÷ [9-(10-5)] = 0.25 (hours) = 15 (minutes).
Running time 1 km15-[9-(10-5)] =11(minutes).
Operating speed is1÷11/60 =1× 60/1= 5.5 (km) per hour.
A: The running speed in Sun Liang is 5.5 kilometers per hour.