[tex]\\ \sf\longmapsto 2(5m-4)-3(m-5)^2[/tex]
[tex]\\ \sf\longmapsto 10m-8-3(m^2-10m+5^2)[/tex]
[tex]\\ \sf\longmapsto 10m-8-3(m^2-10m+25)[/tex]
[tex]\\ \sf\longmapsto 10m-8-3m^2+30m-75[/tex]
[tex]\\ \sf\longmapsto -3m^2+30m+10m-75-8[/tex]
[tex]\\ \sf\longmapsto -3m^2+40m-83[/tex]
