To find the rate of the second bus, we need to solve the equation given:
\[ 3(r + 10) + 3r = 282 \]
First, we can distribute the \(3\) on the left side of the equation:
\[ 3r + 30 + 3r = 282 \]
Now, combine the like terms:
\[ 6r + 30 = 282 \]
Next, subtract \(30\) from both sides:
\[ 6r = 252 \]
Now, divide both sides by \(6\):
\[ r = 42 \]
Therefore, the rate of the second bus is:
r = 42 mph