5.4/10.8+2/2.5=54/108+20/25=1/2+4/5=0.5+0.8=1.3
(27.2-23.6)×0.25=27.2×0.25-23.6×0.25=27.2×1/4-23.6×1/4=6.8-5.9=0.9