.
Let x be the time for Brooks, and y be the time for Wong.
The system of equations is
x + y = 70 (1) (the combined time)
40x + 35*y = 2650 (2) (liters total
To solve it, multiply equation (1) by 35 (both sides). Keep equation (2) as is
35x + 35y = 70*35 (3)
40x + 35y = 2650 (4)
Now subtract equation (3) from equation (4). You will get
40x - 35 x = 2650-70*35
5x = 200
x = 200/5 = 40.
ANSWER. Brooks family - 40 hours; Wong family 70-40 = 30 hours.
Solved.
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If you want to see many other similar solved problems, look into the lesson
- The Robinson family and the Sanders family each used their sprinklers last summer
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lesson is the part of this online textbook under the topic "Systems of two linear equations in two unknowns".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
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to your archive and use it when it is needed.