Jawapan

2015-09-04T22:36:12+08:00
(60km/j+80km/j)÷2
140km/j÷2
70km/j
2015-09-05T00:58:49+08:00
Jarak A = 60 km/j X 1 j = 60 km

Jarak B = 80 km/j X  \frac{30}{60} = 40 km

Purata laju keseluruhan perjalanan
= \frac{60+40}{1.5}
= \frac{100}{1.5}
= 66.67 km/j