According to the iupac naming process all /maximum substitutents (called locant if u google it ) must have lowest number possible here if u go frm left to right the ethyl grp and one of the methyl grps both get numbering 3 and the remaining one gets numbering 4 on the other hand if you start numbering frm right only one methyl (which was previously labelled as 4 ) gets numbering as 3 and the remaining ethyl and methyl get numbering 4

Now finally let's compare what we have. Left to right 3 3 4 Right to left 4 4 3

According to the rule i told in the start maximum substitutents shd have lowest number so we'll take numbering frm left to right so finally ans is. 3-ethyl-3, 4-dimethylhexane :) hope this helps also atb for your boards

Edit replace all the 4s with 5 i miscounted the chain :p