Last week, donnell practiced the piano 3 hours longer than marcus. together, marcus and donnelly practiced the piano for 11 hours. for how many hours did each young man practice the piano?

Let the number of hours Donnell practiced be d
and the number of hours Marcus practiced be m.
We can set up a system of equations.
d = m + 3
m + d = 11
Substitute the value of d that's in the first equation, into the second equation.
m + (m + 3) = 11
2m + 3 = 11
2m = 8
m = 4
Marcus practiced for 4 hours. Since Marcus and Donnell, together, practiced 11 hours, Donnell practiced for 11-4=7 hours.