Question 976205
harris is R hrs
hayes is S hrs

R+S=55 hours, 
R=55-S

(55-S)*30=1650-30S units are hours*liters/hour-hours
S*35=35S

Their sum is 1800 L.

1650-30S+35S=1800
5S=150 
S=30 hours
R=25 hours

30*35=1050 L
25*30=750 L
add to 1800 L