def create_equation_from_terms(terms):
    """
    Create a string equation (right hand side) from a list of terms.

    >>> create_equation_from_terms(['x','y'])
    'x+y'
    >>> create_equation_from_terms(['-x', 'y', '-z'])
    '-x+y-z'

    :param terms: list
    :return: str
    """
    if len(terms) == 0:
        return ''
    for i in range(0, len(terms)):
        term = terms[i].strip()
        if not term[0] in ('+', '-'):
            term = '+' + term
        terms[i] = term
    if terms[0][0] == '+':
        terms[0] = terms[0].replace('+', '')
    eqn = ''.join(terms)
    return eqn