So I managed to get it partially resolved. This is the entire problem as it was intended, where I ask students to show steps of the solution; the previous post had just the part where I got stuck ... I still don't understand what went wrong there.
and here is a solution
The only thing I cannot do anymore is assigning partial credit. I figure that is what went wrong before. So (a) is counted correct if both entries are correct and wrong if one (or both) are wrong. C'est la vie.
B.t.w. Dominique if you ar still reading this, can you change "Medecine" to "Medicine" on the page with examples?