0.7X-X=2.7 先同时扩大十倍7X-10X=27
-3X=27
X=-9
0.7x-x=2.7
-0.3x=2.7
x=-9
0.7X(1-10/7)=2.7
0.7X=2.7/(-3/7)
X=-9
0.7x-x=2.7
解:-3x=2.7
x=-9
-0.3x=2.7
x=-9