Let x be the number of children's tickets; then the number of adult tickets is 2x. The revenue equation is then 5x + 6*(2x) = 391. Simplify and solve 5x + 12x = 391 17x = 391 x = 391/17 = 23. ANSWER. 23 children's tickets and 2*23 = 46 adult tickets. CHECK. 5*23 + 6*46 = 391 dollars. ! Correct !