new.sol

contract Parent {
    function add(uint _a, uint _b) public pure returns (uint) {
        return _a + _b;
    }

     function getBalance() public view returns (uint) {
         return address(this).balance;
    }
}

contract Child {
    Parent newA = new Parent();

    function getAdd(uint _a, uint _b) public view returns (uint) {
       return newA.add(_a, _b);
    }

    function getBalance() public view returns (uint) {
       return newA.getBalance();
    }

}