m-m-12=1-m-23⇒2m-m-12=3-m-23⇒2m-m+12=3-m+23⇒m+12=1-m3⇒3m+1=21-m⇒3m+3=2-2m⇒3m+2m=2-3⇒5m=-1⇒m=-15

How to solve

m - \frac{m - 1}{2} = 1 - \frac{m - 2}{3} \Rightarrow \frac{2 m - (m - 1)}{2} = \frac{3 - (m - 2)}{3} \Rightarrow \frac{2 m - m + 1}{2} = \frac{3 - m + 2}{3} \Rightarrow \frac{m + 1}{2} = \frac{1 - m}{3} \Rightarrow 3 (m + 1) = 2 (1 - m) \Rightarrow 3 m + 3 = 2 - 2 m \Rightarrow 3 m + 2 m = 2 - 3 \Rightarrow 5 m = - 1 \Rightarrow m = - \frac{1}{5}