.
The drinking rate is = gallons per minute.
In 24 minutes, the camel drinks = 2*8 = 16 gallons.
Hence, after 24 minutes, he drinks the rest 30-16 = 14 gallons. ANSWER
--------------
Solved, completed, explained and calculated.
Happy learning (!)
/\/\/\/\/\/\/\/
The answer by @josgarithmetic, giving 16 gallons, is I N C O R R E C T.
For your safety, simply ignore it.