Okay so the question is:

Question

"Three people are cheering simultaneously. Measured individually, the cheers are 80dB, 80dB, and 50dB. What would the cheering measure totally? Use your knowledge of logarithms to solve."

So the formula we were given a few days ago was:
dB=10log(I/Io)

All I've done so far is plugged the dB values into the equation to get:
8=log(I1/Io), 8=log(I2/Io), and 5=log(I3/Io)

Where do I go from here? I'm lost :/