Dan and Makiko started their homework at the same time. It took Dan twice as long as Makiko, plus 40 minutes. Which system of equations could be used to find d (Dan's time) and m (Makiko's time)?
A) d=2m, d=m+40
B) d=m+40, d=2m+40
C) d=2m−40, m=d+40
D) d=m, m=d−40