20 questions 1 1.9 m2122 questions 48 0.12 80.5 ~ 90.51184 people 23 questions.
24 questions c( 1, 3) 25 questions literature book unit price 8 yuan popular science book 12 yuan can also buy at least 46 26 questions (1)(2) questions omitted (3)2 27 questions 80 40 60 55 liters/minute analytical formula omitted 28 questions whose total score is less than or equal to the sign cannot be typed out, so omitted (3).