I got through 3 problems involving decibels, and now it asks me this: "How many times more intensity does a sound of 47dB have than a sound of 42dB?"

The decibel equation is: D = 10 log(I/10^-16) where I is intensity($\displaystyle W/cm^2$) and D is decibels. And I might mention, intensity is in 10^-n and n is a number lower than 16