A motorcycle covered the first 60 km of its journey at an average speed of 40 km/h. The speed of the motorcycle for covering the rest of the journey, i.e. 90 km, was 45 km/h. During the whole journey, the overall average speed of the motorcycle was:
1
\(42\frac{1}{7}\) km/h
2
\(42\frac{1}{2}\) km/h
3
42 km/h
4
\(42\frac{6}{7}\) km/h