[latex] frac{x+4y}{12}+ frac{2x+5y}{12}= frac{3c+9y}{12}^{(3}= frac{x+3y}{4} \ \ frac{6c^2}{3c-2} -^{3c-2)}2c-^{3c-2)}5= frac{6c^2}{3c-2} - frac{6c^2-4c}{3c-2}- frac{15c-10}{3c-2}= frac{-11c-10}{3c-2} [/latex]

              [latex] frac{x+4y}{12} + frac{2x+5y}{12} = frac{x+4y+2x+5y}{12} = frac{3x+9y}{12}=frac{3(x+3y)}{3*4} =frac{(x+3y)}{4}[/latex] [latex] frac{6 c^{2} }{3c-2} - 2c-5 = frac{6 c^{2} }{3c-2} - frac{(2c+5)(3c-2)}{3c-2}= \ \= frac{6 c^{2} }{3c-2} - frac{(6c^{2}+15c - 4c-10)}{3c-2}= \ \= frac{6 c^{2} }{3c-2} - frac{(6c^{2}+11c -10)}{3c-2} = \ \= frac{6 c^{2} -(6c^{2}+11c -10) }{3c-2}= \ \ = frac{6 c^{2} -6c^{2}-11c +10}{3c-2}= oxed{ frac{-11c +10}{3c-2}}[/latex]