david has $ 2,400 at the beginning of his trip , after spending money , he still has exactly $ 800 less than he spent on the trip . how much money does john still have ?
"suppose total money spent = x not spend ( money he still has ) = x - 800 x + x - 800 = 2400 x = 1600 money not spend = 1600 - 800 = 800 answer : d"
subtract(divide(add(add(multiply(const_100, const_10), 800), 800), const_2), 800)