(m+1-1/1- m):(1-2a-3b/2a+3b)

(m+1-1/1- m):(1-2a-3b/2a+3b)=

(m /1- m) : (1-(2a+3b) / 2a+3b)=

(m /m(1/m - 1) : (2a+3b)(1/(2a+3b)-1) / (2a+3b)=

1 /(1/m - 1) : (1/(2a+3b)-1) =

1 /(1/m - 1)(1/(2a+3b)-1)