It should cost $1.65 for each large drink.
You subtract $12 to $16.95 and that would give you 4.95 and divide it to the number of drinks they bought which is 3 and that would give you $1.65
First example:
Subtract the 8n on both sides to get the variable on one side of the equation. Do the same for the regular numbers. Then divide by -3.

This should be your final answer.
Second Example:
Do the same thing as explained in Example 1. Here's some work to help guide you.

That should be your final answer here.
Third Example:

Hope this helps and its understandable! Let me know if you still don't understand.
Answer:
If you multiply any irrational number by the rational number zero, the result will be zero, which is rational. Any other situation, however, of a rational times an irrational will be irrational.
The answer is (, )=(6−2, )