Question 1049152
Let r/60 be Marie's pace in minutes. Then Donnie's pace is r+1/60. So:
40r/60=36(r+1)/60
36r+36=40r
4r=36
r=9
Marie goes 9/60 miles per minute, or 9 miles an hour; Donnie goes 10 mph.
Both Donnie and Marie (ha ha) go 6 miles. ☺☺☺☺