Why is the gcf of two numbers sometimes one

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

Which composition of similarity transformations maps polygon abcd to polygon a'b'c'd'? a dilation with a scale factor less than 1 and then a reflection a dilation with a scale factor less than 1 and then a translation a dilation with a scale factor greater than 1 and then a reflection a dilation with a scale factor greater than 1 and then a translation

How do i do this activity, is appreciated