Answer:
$138
Step-by-step explanation:
When marking up a price, all you have to do is consider the the original value, and add that to the percentage of that value.
In this case, we know that the original price is $120.
15% of 120 is 18, so we simply add 18 to 120.
18 + 120 = 138
The watch will now cost $138.
