The large hose fills 1 pool in 9 hours written as 1/9
The small hose fills 1 pool in 18 hours, written as 1/18
Now you have 1/9 + 1/18 = 1/x ( x is the unknown time for both hoses).
rewrite 1/9 with a common denominator as 1/18:
1/9 = 2/18
Now you have 2/18 + 1/18 = 1/x
Add the left side:
2/18 + 1/18 = 3/18
Now you have 3/18 = 1/x
Cross Multiply:
3x = 18
Divide both sides by 3"
x = 18/3
X = 6
It will take both hoses 6 hours.
Answer:
the constant of proportionality is 4
5x+3y=12
Subtract 5x from both sides
3y=-5x+12
Divide by 3
Y=-5/3x +4
