80×61-67.2÷32
=4880-2.1
=4877.9
[9-(5+1/4)]÷[4+1/3-(1+3/4)]
=[9-5-1/4)]÷[4+1/3-1-3/4]
=[4-1/4]÷[3+1/3-3/4]
=(11/4)÷[3-5/12]
=(11/4)÷(31/12)
=11/4*12/31
=11*3/31
=33/31
=1+2/31
=1又2/31
54237-408×28÷24
=54237-17×28
=54237-476
=53761
(1+1/5)[5*(6+3/5)÷1.8-(3+1/4)]
=(6/5)[5*33/5÷9/5-13/4]
=(6/5)[5*33/5*5/9-13/4]
=(6/5)[55/3-13/4]
=(6/5)(181/12)
=6/5*181/12
=181/10
=18+1/10
=18又1/10