Answer:
Martin family: 20 hours
Lewis family: 35 hours
Step-by-step explanation:
Let's say that the Lewis family sprinklers were out for L hours and the Martin family's sprinklers were out for M hours. We know that for each hour that the Lewis family sprinkler was on, 30L of water was put out. We can thus write the Lewis family sprinkler water output as 30L per each hour of L = 30 * L. Similarly, the Martin family sprinkler water output = 15 * M .
We know that the total hours for the sprinklers is 55, so L + M = 55. The total water output for the sprinklers is the sum of the sprinkler outputs, so 30 * L + 15 * M = 1350
L + M = 55
30 * L + 15 * M = 1350
One way to solve this would be to solve for L in the first equation and substitute that into the second
subtract M from both sides in the second equation
55 - M = L
30 * (55-M) + 15 * M = 1350
30 * 55 - 30 * M + 15 * M = 1350
1650 - 15M = 1350
subtract 1650 from both sides to isolate the M and its coefficient
-15M = -300
divide both sides by -15 to isolate M
M = 20
L = 55-20 = 35
