Identify the determiner in the following sentence: Make new friends, but keep the old; those are silver, these are gold.

Determiners are words such as the, my, this, some which are used before nouns. Determiners include the following common types:

Articles: a, an, the
Demonstratives: this, that, these, those
Possessives: my, your, his, her etc.
Quantifiers: some, many, few, one, two etc.
আলোচ্য বাক্যে these এবং those থাকলেও এগুলো noun এর পূর্বে ব্যবহৃত হয়নি। অতএব, এগুলো determiner নয়।
‘old’ এখানে old friends অর্থে noun এর কাজ করছে এবং এর আগে ‘the’ determiner হিসেবে ব্যবহৃত হয়েছে।

Source: Cambridge Dictionary