Answer:
Nguyen family uses sprinkler for 35 hours while the Hall family uses sprinkler for 15 hours
Step-by-step explanation:
Let h and n be the number of hours that the Hall and Nguyen family individually use their sprinkler for, respectively. Since they use for a combined total of 50 hours, h + n = 50, or h = 50 - n
Also their total water output is 1050 L, we can have the following equation
35h + 15n = 1050
Substitute h = 50 - n and we have
35(50 - n) + 15n = 1050
1750 - 35n + 15n = 1050
35n - 15n = 1750 - 1050
20n = 700
n = 35 hours
h = 50 - n = 50 - 35 = 15 hours