Re write log (AB) as log a + log b= 4
Log(A/B) as log a - log b = 12
now add the 2 equations together
2log a = 16
log a= 8.
substitute value of log a back into either equation to solve for log b
8 + log b = 4
log b = -4
so log a/log b = 8/-4 = -2
Interesting way to make you use your log rules