Machine Gun Kelly and Avril Lavigne are bringing their world tour to the Derby City this summer, and tickets for the concert go on sale this week.Yum! Center officials revealed the mystery behind a cryptic social media post that only showed a photo of the downtown arena in pink with the numbers "07.02." The post included the sentence, "It's complicated... check back soon."Turns out the pink was for Machine Gun Kelly's "Mainstream Sellout" tour, which features Lavigne and iann dior. The trio will make their way to the Yum! Center on Saturday, July 2.Tickets for the concert go on presale March 23 and for the public on March 25. Click here for information.Other stops include Cleveland, Miami, Boston and Los Angeles.More information and updates can be found online.