i have no clue on how to start this one.The loudness of sound is measured in decibels in honor of Alexander Graham Bell (1847-1922), inventor of the telephone. If the variation in pressure is P pounds per square inch, then the loudness L in decibels is $\displaystyle L = 20 \log_{10}(121.3 P)$

Find the variation in pressure caused by a rock band at 115 decibels.