Spoiler: Hidden Answer Take {rat, cat, dog} as {x, y, z} and solve these equations x+y = 10 x+z = 20 y+z = 24 When you solve this you get {rat, cat, dog} = {3, 7, 17} So to answer the question : rat + cat + dog = 3 + 7 + 17 = 27 You could also add all the equations (as you have not asked the individual weights) Add all the 3 equations above : you will get 2x + 2y + 2z = 54 Divide the equation by 2 : x + y + z = 54/2 = 27 rat + cat + dog = 27
