because its an english problem (semantics) not a math one.  most english speakers assume a comma after $1: > book costs $1, plus half its price.  book = $1  1/2 price = 50 total = $1.50 non-english (brown) either assume a comma after "costs" and interpret it as a math problem: > book costs, $1 plus half its price.  book = $1 + (1/2 book price) book = 1 + (book / 2) book - (book / 2) = 1 book / 2 = 1 2*(book/2) = 2*1 book = 2
United States