We need to plot 1.4 and 1.4+h on the number line.
We know that h is the additive inverse of 1.4. The additive inverse of any number is the number which when added to the former number results in zero (0).
⇒ 1.4 + h = 0
⇒ h = -1.4
Hence, Sum = 0
Please refer to the attached image to see 'h', '1.4' and '1.4 + h' marked on the number line