Admit when someone lost to trickery an not knowledge.

I think it would ease frustration if someone gets a word problem wrong because of trickery in the wording of a problem and not knowledge of the algebra involved, you'd let them know. An example is a word problem where someone paints square meters at a constant rate and has a constant rate of clean up time. Its a slope and y intercept problem. Walking through the table you see it takes the person 0.05 hours to paint 1 square meter and there's a 0.5 hour cleanup time ( the y intercept). The table shows  how long each job takes ( 30 square meters, 45 square meters etc.) Each point in that table INCLUDES the cleanup time. The question asks, "how long would it take the person to paint one square meter?" My answer is 0.55 hours. 0.05 hours to paint the square meter and .5 hours to clean up. Wrong, 0.05 hours- do 7 more questions. Did I misunderstand the algebra or did I misunderstand the deceit? How about this instead of wasting my time: " How long does it take to paint 1 square meter EXCLUDING cleanup time?" Or just saying "You got it wrong because we tricked you- you understood the points involved!"  I don't see how this type of trickery helps anyone. On Kahn academy, I know the answer for 5  minutes but I'm looking for the angle or the trick. That's not teaching me algebra. Its eroding my confidence and slowing me down.