Three guys go to the bar and get £30 worth of drinks. They pay £10 (10*3=30) each and the waitress takes the money. Before she puts it in the till the manager notices the guys and tells her “I know these guys, give them a £5 discount”
On the way to their table the waitress decides to give the guys £3 back and keep £2 as a tip.
The guys take a pound each, so instead of paying £10 each they end up paying £9 each (9*3=27).
And the question is: if they ended up paying £27 and the waitress kept £2 where did the last pound go?
In: 397
A big part of math is learning how to translate problems from a spoken language into math and back. Algebra is hard and people are bad at it. That problem relies on people making a translation mistake, the guys paid 27 and got 3 back so the right calculation is either Total spent – change = Bill including tip (30-3=27) or pretip bill plus tip equals total spent (25+2 = 27) but the problem sets up the problem as 30-2 = 27 which is obviously wrong once translated to math, but it’s hard to see where you made the translation error.
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