Use logb (5)=1.609 and or logb (8)=2.079 to find logb 40
logb 40=____???
log b 5 = 1.609 log b 8 = 2.079
Note that
log b 5 + log b 8 = log b (5*8) = logb 40
1.609 + 2.079 = log b 40
3.688 = log b 40
+318 
