【1】2.65+0.45÷0.15-1.65【2】【17/20-（2/5+1/4）】÷4/5

题目

【1】2.65+0.45÷0.15-1.65【2】【17/20-（2/5+1/4）】÷4/5

答案

【1】2.65+0.45÷0.15-1.65
=（2.65-1.65)+0.45÷0.15
=1+3
=4
【2】【17/20-（2/5+1/4）】÷4/5
=(17/20-2/5-1/4)×5/4
=17/20×5/4-2/5×5/4-1/4×5/4
=17/16-1/2-5/16
=17/16-5/16-8/16
=4/16
=1/4