分析:(1)先計(jì)算X+40%X=1.4X,然后等式的兩邊同時(shí)除以1.4即可;
(2)先計(jì)算X-25%X=0.75X,然后等式的兩邊同時(shí)除以0.75即可;
(3)先計(jì)算X-65%X=0.35X,然后等式的兩邊同時(shí)除以0.35即可;
(4)先計(jì)算X+75%X=1.75X,然后等式的兩邊同時(shí)除以1.75即可;
(5)先計(jì)算X-8%X=0.92X,然后等式的兩邊同時(shí)除以0.92即可.
解答:解:
(1)X+40%X=42,
1.4X=42,
1.4X÷1.4=42÷1.4,
X=30;
(2)X-25%X=15,
0.75X=15,
0.75X÷0.75=15÷0.75,
X=20;
(3)X-65%X=0.7,
0.35X=0.7,
0.35X÷0.35=0.7÷0.35,
X=2;
(4)X+75%X=3.5,
1.75X=3.5,
1.75X÷1.75=3.5÷1.75,
X=2;
(5)X-8%X=1.38,
0.92X=1.38,
0.92X÷0.92=1.38÷0.92,
X=1.5.
點(diǎn)評(píng):本題主要考查解方程,根據(jù)等式的性質(zhì)進(jìn)行解答即可.