The second and last one.
The second one multiplies the cost of each type of ticket by two, therefore saying that you wanted to buy two of each type of ticket.
The last one multiplies the cost of a single ticket of all three types and multiplies it by 2.
When you see a "%" you need to ask " a percent of what"?
Here, it's a percent of the original prize, so the discount is 20% of the original prize, that is 20% of 35.
20% is also 20/100 or 1/5, so we can calculate this like this:

so the discount is 7 dollars.
It's D the comunicative property of addition