Răspuns :
Folosim regula de 3 simpla:
12,7km..............1h
X.........................4h
X=12,7×4/1
X=50,8/1
X=50,8 km
12,7km..............1h
X.........................4h
X=12,7×4/1
X=50,8/1
X=50,8 km