We need factors that when multiplies give us: (4*-7)=-28
We also need factors that when added up give us: +27
These factors are: +28,-1
Thus we get,
(x+7)=0 AND (4x-1)=0
Resulting values of x becoming,
x=-7 AND x=(1/4)
Solution set={-7,1/4}
Hope this helps,
best of luck