5.4÷1又1/9+3.6×1/10+0.9=5.4÷10/9+3.6×0.1+0.9=5.4x0.9+0.9x0.4+0.9=（5.4+0.4+1）x0.9=6.8x0.9=6.12
5.4÷1又1/9+3.6×1/10+0.9=5.4×0.9+0.36+0.9=0.9×(5.4+0.4+1)=0.9×6.8=6.12..
