Solution below!  The only changed code is in the mapStateToProps function and in the renderList method. 

• The mapStateToProps function was updated to communicate the favoriteTitle piece of state into the component

• Because the mapStateToProps function is now returning an object with a favoriteTitle property, the React component now has access to a prop of this.props.favoriteTitle

• The mapping function inside of renderList compares the title of the current song it is iterating over to this.props.favoriteTitle

import React from 'react';
import { connect } from './react-redux';

class _SongList extends React.Component {
    renderList() {
        return this.props.songs.map(song => {
            return (
                <div className="item" key={song.title}>
                    <div className="right floated content">
                        <div className="ui button primary">Select</div>
                    </div>
                    <div className="content">
                        {song.title}
                        <div>
                            <b>{song.title === this.props.favoriteTitle && 'Favorite!'}</b>
                        </div>
                    </div>
                </div>
            );
        });
    }

    render() {
        return <div className="ui divided list">{this.renderList()}</div>;
    }
}

const mapStateToProps = state => {
    return { songs: state.songs, favoriteTitle: state.favoriteTitle };
};

export const SongList = connect(mapStateToProps)(_SongList);