21. Gill leaves Lille by train at 09:00. The train travels the first $27 \mathrm{~km}$ at $96 \mathrm{~km} / \mathrm{h}$. It then stops at Lens for 3 minutes before travelling the final $29 \mathrm{~km}$ to Lillers at $96 \mathrm{~km} / \mathrm{h}$. At what time does Gill arrive at Lillers?
A $09: 35$
B 09:38
С 09:40
D $09: 41$
E 09:43
Solution: $\mathbf{B}$
Gill travels $27+29=56 \mathrm{~km}$ at $96 \mathrm{~km} / \mathrm{h}$. This takes $\frac{56}{96}=\frac{7}{12}$ th of an hour, that is, $\frac{7}{12} \times 60=35$ minutes. The train stops at Lens for 3minutes, so the journey takes 38 minutes all together. So Gill arrives at Lillers at 09:38.