Daniel rode his bicycle at a constant speed. After 40 minutes, he cycled $24 \mathrm{~km}$. How far did he cycle in 30 minutes?
(A) $12 \mathrm{~km}$
(B) $14 \mathrm{~km}$
(C) $16 \mathrm{~km}$
(D) $18 \mathrm{~km}$
(E) $20 \mathrm{~km}$

## Part B: Each correct answer is worth 6.
Since Daniel rides at a constant speed, then, in 30 minutes, he rides $\frac{3}{4}$ of the distance that he does in 40 minutes.

Therefore, in 30 minutes, he rides $\frac{3}{4} \times 24=18 \mathrm{~km}$.

ANSweR: (D)