Can someone please help me with math you will probably will have to use desmos to answer it.

For what values of b will f(x)= logbx be a decreasing function? (16 )

Which is the value of this expression when p=3 and q=-9

Moesha is (3g+1) years old and shanti is twice moesha age. find the sum of the ages of moesha and shanti in 2 years time. how old will shanti be when moeshas age in twice her present age? find how old moesha and shanti were 4 years ago if g= 5