import { add } from './add' ; export function subtract ( number1 , number2 ) { number1 = number1 . toString ( ) ; number2 = number2 . toString ( ) ; number2 = negate ( number2 ) ; return add ( number1 , number2 ) ; } export function negate ( number ) { if ( number [ 0 ] == '-' ) { number = number . substr ( 1 ) ; } else { number = '-' + number ; } return number ; }