Answer:
Tran family's sprinkler was used for 20 hours
Green's family's sprinkler was used for 30 hours
Step-by-step explanation:
Let the hours for which Tran family's sprinkler used is x hours
water output rate for the Tran family's sprinkler = 35L per hour
water output from Tran family's sprinkler in x hours = 35*x L = 35x
Let the hours for which Green family's sprinkler used is y hours
water output rate for the Green family's sprinkler = 40L per hour
water output from Green family's sprinkler in x hours = 40*y L = 40y
Given
The families used their sprinklers for a combined total of 50 hours
thus
x + y = 50 -------------------equation 1
y = 50-x
total water output of 1900L
35x+40y = 1900 -------------------equation 1
using y = 50-x in equation 2, we have
35x + 40(50-x) = 1900
35x + 2000 - 40x = 1900
=> -5x = 1900 - 2000 = -100
=> x = -100/-5 = 20
y = 50-20 = 30
Thus,
Tran family's sprinkler was used for 20 hours
Green's family's sprinkler was used for 30 hours
