Step by step:
1) we want to get the numbers to one side and the letters to one side
In order to get -1.4 to the right side, we cancel it from the left and take it to the right. In order to cancel -1.4 we had +1.4 to both ends which leaves us with 0 on the left and 2.0 to the right (1.4+0.6)
Therefore:
X=2.0
