Answer :
C = hours Carlos drove, M = hours Maria drove.
52*C+54*M = 217
C = 4,1-M
52*(4,1-M)+54M = 217
213,2-52M+54M = 217
217-213,2 = 54M-52M
3,8 = 2M
M = 1,9
Maria drove 1,9h.
52*C+54*M = 217
C = 4,1-M
52*(4,1-M)+54M = 217
213,2-52M+54M = 217
217-213,2 = 54M-52M
3,8 = 2M
M = 1,9
Maria drove 1,9h.