I have 2 viewmodels say,

viewmodel is bound to view

class A : INotifyPropertyChanged
{
public A(){}

private bool _propertya;
public bool PropertyA
{
get{return _propertya;}
set{_propertya=value; onPropertyChanged("PropertyA");}
}

private void onPropertyChanged(string propertyName)
{
    if (PropertyChanged != null)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}
public event PropertyChangedEventHandler PropertyChanged;
}

And another viewmodel where my properties are linked to another view

class B : INotifyPropertyChanged
{
public B(){}

private bool _propertyb;
public bool PropertyB
{
get{ return _propertyb;}
set{_propertyb=value; onPropertyChanged("PropertyB");}
}
private void onPropertyChanged(string propertyName)
{
    if (PropertyChanged != null)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}
public event PropertyChangedEventHandler PropertyChanged;
}

When PropertyB is changed , I want to check the value of PropertyA from another viewmodel and return bool value based on condition. How can i get the instance of PropertyA from another viewmodel in class B