0.27乘5.6加（）乘5.6加5.6乘025=0.78乘0.565.6乘0.25 没学过x,也没学过负数，

-51.22
设这个数是x
0.27*5.6+5.6x+5.6*0.25=0.78*0.56
5.6(0.27+0.25+x)=0.78*0.56
0.56(5.2+10x)=0.78*0.56
5.2+10x=0.78
x=0.442

提取5.6
就得到5.6乘(0.27加0.25加（）)=0.78 乘0.56=5.6乘0.078
两边都有5.6
于是
0.27加0.25加（）=0.078
最后得()=0.078减(0.27加0.25)=-0.442

先设那个数为X
再把这个数换成X代进去，得方程：
0.27*5.6+5.6*X+5.6*0.25=0.78*0.56
5.6（0.27+X+0.25）=0.078*5.6
0.27+X+0.25=0.078*5.6/5.6
0.52+X=0.078
X=0.078-0.52
X=-0.442

0.27*5.6+( )*5.6+5.6*0.25=0.78*5.6
0.78-0.27-0.25=0.26

设那数为X
0.27*5.6+5.6X+5.6*0.25=0.78*0.56
5.6*(0.27+X+0.25)=0.078*5.6
0.52+X=0.078
X=-0.442