For writing the following structure, the no,-1 is given to which end?
`underset(7)overset(1)(C H_(3)) - underset(6)overset(2)(CH_(2))- underset(underset(underset(underset(CH_(3))(|))(CH_(2)))(5|))overset(2)(CH)- underset(underset(CH_(3))(4|))overset(overset(CH_(3))(4|))(C )- underset(3)overset(5)(CH_(2))- underset(2)overset(6)(CH_(2))- underset(1)overset(7)(C H_(3))`

Explanation

(i) If left side no-1 is given then name is 3-ethyl-4, 4-dimethyl (ii) If right side no, -1 is given then name is 5-ethyl-4, 4-dimethyl. In left side the ethyl substitute get lower no-3 according to alphabetical order
`therefore` So, In structure no. 1 is start at left side end