Format estimated close date for Dynamics 365 Opportunity

[MitchC3]

I have a flow that creates a new record (in Opportunities) in Dynamics 365 when a new email arrives. I can't figure out how to format the date for the expected close date field. I want the expected close date to be 30 days from when the email is received.

I have tried a couple things but most recently set it to: 

formatDateTime(addDays(triggerBody()?['DateTimeReceived'],30),'MM/dd/yyyy')

The dates in Dynamics are displayed as MM/dd/yyyy so I'm not sure why this doesn't work.

The error message I get is: "Cannot convert the literal '08/25/2018' to the expected type 'Edm.DateTimeOffset'."

[MitchC3 · Accepted solution]

formatDateTime(addDays(triggerBody()?['DateTimeReceived'],30),'yyyy-MM-dd' works