Answer:
5*(17-18)
Step-by-step explanation:
"the difference of 17 and 18" can be written as:
(17-18)
"five times" can be written as 5x
Put them together to get: 5*(17-18)
Be aware that one could interpret "difference of 17 and 18" as (18-17), as well as (17-18), as I've done here.