Answer:
Let's denote Carina's average speed as \(s\) (in miles per hour). Carina's brother drove 15 miles per hour faster, so his speed is \(s + 15\).
Carina's distance to Buttonwillow is \(3s\) (since she drove for 3 hours), and her brother's distance is \(4(s + 15)\ (since he drove for 4 hours at a faster speed).
The sum of their distances should be the distance between Anaheim and Berkeley, which is 410 miles:
\[3s + 4(s + 15) = 410\]
Now, solve for \(s\) to find Carina's average speed. Once you have \(s\), you can find Carina's brother's speed by adding 15.