估算57×74≈ 45×19≈ 440÷9≈194÷6≈ 410÷7≈
15.8-(6+÷12.5%)
10-÷×1
325×0.36+6.75×36
5.6×0.375+×5.4-0.375×0.9
5.6x+4x=17.28