Linda lived next to an 86-year-old woman named Margaret. Margaret was home-bound, she couldn't
drive any more, and lived on a low fixed income. She had no children or relatives in the area. For the
past two years, Linda would help Margaret by buying groceries, taking her to doctor appointments,
cleaning up around the house, and picking up her prescriptions. One day, Linda told Margaret that
she should change her will to leave her house to Linda. Margaret refused, saying she planned on
leaving the property to her church. Linda then told her that if she didn't change her will, she would
no longer be able to help Margaret. Margaret changed her will. Is the agreement valid?