分析:算式(1)可根據(jù)乘法交換律進(jìn)行計(jì)算;
算式(2)(3)可根據(jù)乘法分配律進(jìn)行計(jì)算;
算式(4)根據(jù)四則混合運(yùn)算的運(yùn)算順序計(jì)算即可:先算乘除,再算加減,有括號(hào)的要先算括號(hào)里面的;
算式(5)可根據(jù)比例的基本性質(zhì):比例中的兩外項(xiàng)之積等于兩內(nèi)項(xiàng)之積,以及等式的基本性質(zhì):等式兩邊同時(shí)乘以,除以,加上、減去同一個(gè)數(shù),等式仍然成立;
算式(5)根據(jù)等式的基本性質(zhì)解方程即可.
解答:解:(1)
×÷×,
=
÷×
×
,
=
;
(2)
×6.7+4.3×0.75-75%=0.75×6.7+4.3×0.75-0.75,
=(6.7+4.3-1)×0.75,
=10×0.75,
=7.5;
(3)
(+-)×30=
×30+
×30-
×30,
=21+25-24,
=22;
(4)
[1-(-)] ×=[1-(0.5-0.25)]×
,
=[1-0.25]×
,
=0.75×
,
=0.5;
(5)
:=:x x=
×
x
÷=
×
÷,
x=
;
(6)x+
x=60
x=60,
x
÷=
60÷ x=48.
點(diǎn)評(píng):完成本題要細(xì)心分析式中數(shù)據(jù)的特點(diǎn),然后選擇合適的方法進(jìn)行計(jì)算.