We can multiply the number of items by the price of each item to find the total cost:

The total cost is $109.
If we have a 40% discount, we have to substract it from the total cost.
The discount is equal to 40% of the total cost, so we can calculate the discount as:

Then, we will pay a total cost with discount of:

The total including the discount is $65.40.
NOTE: we could also have calculated it as 109*(1-0.4)=109*0.6=65.40.