The ice without salt will melt first because in the mixture of
ice and salt ,the presence of salt increase the melting point of
ice.
Example:----
When i was fourteen year old my favourite ice cream was MATKA
KULFI. Once a day i felt some salty test in the KULFI, i asked the
reason of salty test then the KULFI saler
told me that he put the covered kulfi in the mixture of salt and
ice to prevent kulfi to melt salt provide thermal isolation to ice
and increase melting point of ice.