Answer:
Hills: 25 [hours]; Moores: 35 [hours].
Step-by-step explanation:
all the details are in the attachment, the answer is marked with orange colour:
1) to make up the first equation of the system;
2) to write two equations as the system (the 2-d equation is from condition), then to solve this system.
Note, Rate(H) means 'the water output rate for the Hill family's spinker', Rate(M) means 'the water output rate for the Moore family's spinker'.
