Title: Trans-Siberian Orchestra

Content:
Trans-Siberian Orchestra (TSO) is an American progressive rock band founded around 1993 by producer, composer, and lyricist Paul O'Neill, who brought together Jon Oliva and Al Pitrelli (both members of Savatage) and keyboardist and co-producer Robert Kinkel to form the core of the creative team.  The band gained in popularity when they began touring in 1999 after completing their second album, "The Christmas Attic" the year previous.  In 2007, the "Washington Post" referred to them as "an arena-rock juggernaut" and described their music as "Pink Floyd meets Yes and The Who at Radio City Music Hall."  TSO has sold more than 10 million concert tickets and over 10 million albums.  The band has released a series of rock operas: "Christmas Eve and Other Stories", "The Christmas Attic", "Beethoven's Last Night", "The Lost Christmas Eve", their two-disc "Night Castle" and "Letters From the Labyrinth".  Trans-Siberian Orchestra is also known for their extensive charity work and elaborate concerts, which include a string section, a light show, lasers, "enough pyro to be seen from the International Space Station", moving trusses, video screens, and effects synchronized to music.

Title: Tru Collins

Content:
Tru Collins is an American actress and indie-pop singer.  She is known for her role of Julie on MTV's original high school comedy, Awkward.  Tru was born in Richmond, Virginia to five-time Emmy Award winning television journalist Reid Collins and choreographer Lindy Fisher.  She attended Manhattan's Professional Performing Arts School at 15 while studying classical piano and training with Elaine Kudo of American Ballet Theatre.  Collins began college with a songwriting scholarship from Universal and studied at New York University and The New School in New York City.  In 2014, she guest starred on Showtime's period drama Masters of Sex opposite Michael Sheen and had a supporting role in Spring Awakening, an indie film set in the late 1800s.  Tru has recurred as mean girl Julie on MTV's Awkward seasons 2 - 5.  As a singer, she performed with Grammy-winning soul singer Latrice Varrett, opening for Aretha Franklin at the Nokia Theatre Times Square in 2009.  In 2010, she joined Atlantic Records' multi-platinum progressive rock band Trans-Siberian Orchestra as a vocalist, touring arenas across North America and promoting the band performing acoustic guitar/vocal solos live on numerous rock radio stations.  That year, TSO reached #12 on the Billboard charts for American Arena Tours, beating Taylor Swift and Justin Bieber.  The tour grossed $47,395,108 and sold out 51 arenas.  She has co-written songs with Rostrum Records artist Vali and Three 6 Mafia's Juicy J, and her work has been featured on various recordings and television soundtracks.  In 2012, Collins performed with DJ Ravi Drums, Kitara player Craig Dobbin, and rapper Wes Period at the Air Canada Centre Arena in Toronto.  In 2015, Tru joined Steven Seagal's blues band Thunderbox for a European tour and performed with ten-time Grammy Award winner George Benson at the Cognac Blues Passion Festival in Cognac, France.  Her debut solo EP, "Story of A Gypsy Child", from producer Jonny on the Rocks of Brooklyn bands Shinobi Ninja and Rocky Business, is set for 2015 release.  Her music video for the first single, "Party Dress", was released via YouTube in February 2015.

Question: The rock band joined by Tru Collins in 2010 has sold approx. how many concert tickets?
Answer: 10 million