(1992X584-380)分之(204+584X1991)-89分之5
=(1991X584+584-380)分之(204+584X1991)-89分之5
=(1991X584+204)分之(204+584X1991)-89分之5
=1-89分之5
=89分之84
(1992X584-380)分之(204+584X1991)-89分之5
=(1991X584+584-380)分之(204+584X1991)-89分之5
=(1991X584+204)分之(204+584X1991)-89分之5
=1-89分之5
=89分之84