The Big Bang Theory/The Line Substitution Solution
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The Line Substitution Solution is the twenty-third episode of the ninth season of The Big Bang Theory, and the two hundred sixth episode overall.
Starring: Johnny Galecki (Dr. Leonard Hofstadter), Jim Parsons (Dr. Sheldon Cooper), Kaley Cuoco (Penny Hofstadter), Simon Helberg (Howard Wolowitz), Kunal Nayyar (Dr. Rajesh "Raj" Koothrappali), Mayim Bialik (Dr. Amy Farrah Fowler), Melissa Rauch (Dr. Bernadette Rostenkowski-Wolowitz), Kevin Sussman (Stuart Bloom)
Guest Starring: Blake Anderson (Trevor)
Co-Starring: Amanda Payton (Ainsley)