42:45 If A and B have the same four subspaces, then they have the same reduced row echelon form.####[['A', 'Mathematical_Related_Concept', 'NEU'], ['B', 'Mathematical_Related_Concept', 'NEU'], ['subspaces', 'Mathematical_Related_Concept', 'NEU'], ['row echelon form', 'Mathematical_Related_Concept', 'NEU']]