Working alone at their respective constant rates, machine a and machine b can fill a certain order in 3 hours and 6 hours, respectively. if the two machines work simultaneously at their respective constant rates, how many hours does it take the two machines to fill?

2 hours

Step-by-step explanation:

Given : Working alone at their respective constant rates, machine A and machine B can fill a certain order in 3 hours and 6 hours, respectively.

Let t be the time taken by both of them working together.

Then, according to the question, we have

Hence, it will take 2 hours by the two machines .

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18