#### Answer

(a) Beth gets to San Francisco first.
(b) Beth has to wait for 20 minutes for Alan to arrive.

#### Work Step by Step

We can find Alan's driving time.
$t = \frac{d}{v} = \frac{400~mi}{50~mph}$
$t = 8 ~hours$
Since Alan leaves at 8:00 am, Alan arrives at 4:00 pm.
We can find Beth's driving time.
$t = \frac{d}{v} = \frac{400~mi}{60~mph}$
$t = 6.67 ~hours$
$t = 6 ~hours~and~40~minutes$
Since Beth leaves at 9:00 am, Beth arrives at 3:40 pm.
(a) Beth gets to San Francisco first.
(b) Beth has to wait for 20 minutes for Alan to arrive.