john has $ 1,200 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 = 1200 x = 1000 money not spend = 1000 - 800 = 200 answer : a"
subtract(add(multiply(const_100, const_10), 800), divide(add(800, add(multiply(const_100, const_10), 800)), const_2))