Answer:
4-ethyl-6-decyne
Explanation:
Counting the carbon atoms from the right gives an ethyl molecule on the 4th carbon.
The 6th carbon atom hosts the functional group, alkyne.
Since the compound is 10 carbon atoms long, with a branch of ethyl on the 4th carbon atom and the alkyne group on the 6th carbon, we hereby call it a 4-ethyl - 6 - decyne.
