if x / y = 2 / 5 , then ( x + y ) / ( x - y ) = ?
any x and y satisfying x / y = 2 / 5 should give the same value for ( x + y ) / ( x - y ) . say x = 2 and y = 5 , then ( x + y ) / ( x - y ) = ( 2 + 5 ) / ( 2 - 5 ) = - 7 / 3 . answer : e .
divide(add(2, 5), subtract(2, 5))