1/2+x=5/6
x=5/6-1/2
x=1/3
x-7/10=1/5
x=1/5+7/10
x=9/10
x+4/1=1/2
x=1/2-1/4
x=1/4………………………………这题题目貌似打错了,直接按1/4做了