A1 and A2 German by Memrise / Replaced courses

Why “sind” if the subjet “das” is singular. Still beats me though. Or should I read “Peter und Sandras Fahrräder sind das.”?

Still waiting for some clarification on that one.

Hi sircemloud,
“these are now Peter and Sandra’s bikes now” is this the english sentence?
Or “these are now Peter and Sandras bikes?”

das Fahrrad = singular
die FahrRÄDER= plural

das sind = these are