1.485－720÷（15×12）=485-720÷12÷15 =485-60÷15=485÷4=4812.3.8×4.4＋0.44×62 =38×0.44+0.44×62=（38+62）×0.44=100×0.44=443.8×（1/48＋125）=8×1/48+8×125=1/6+1000=1000又1/6