-3*6^x-10=-49.1 //// divide both sides by -3
6^(x-10)=16+11/30
log (16+11/30) / log 6= 1.56 = x-10
////// when using log on calculator, its 10^x = (your entery).
to make it (wanted number)^x=(your entery)
we have to divide (log (your entery )) by (log wanted number )///////////
x=11.56
(from your question I assume you don't need an explanation for every simpe action)