5x+6x=33 (5+6)x=3311x=33x=33÷11x=35.8m-4.5m=7.8 （5.8-4.5）m=7.81.3m=7.8m=7.8÷1.3m=6 y-0.28y=12 (1-0.28)y=120.72y=12y=12÷0.72y=16又2/34.2n+2.5n=13.4(4.2+2.5)n=13.46.7n=13.4n=13.4÷6.7n=2