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The James family and the Robinson family each used their sprinklers last summer. The water output rate for the James family sprinkler was 20 L per hour. The water output rate for the Robinson family sprinkler was 25 L per hour .The families used their sprinkler for a combined total of 55 hours,resulting in a total water output of 1275 L. How long was each sprinkler used?
Solution
James : x hrs
Rob: y hrs
x+y = 55…………..eqn (1)
20 x + 25 y = 1275…………..eqn (2)
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20 (55-y) +25 y =1275
solve for y, substitute value of y back in eqn 1
James : x hrs = 20 hrs
Rob: y hrs = 35 hrs