Let the amount of the first brand be x, and let the amount of the second brand be y.
0.09x + 0.14y = 240 * 0.13 .................(1)
x + y = 240 ..............(2)
y = 240 - x .......................(3)
Plugging the value for y from equation (3) into equation (1), we get:

...............(4)
Equation (4) simplifies to:
-0.05x = -2.4
giving the value for the required amount of 9% vinegar as 48 ml and the required amount of 14% vinegar as 240 - 48 = 192 ml.
Let us determine each of their rates of work:
Since Tiana can clear the field in 3 hours, meaning she can do 1/3 of the work per hour.
In the same way, Jacob can do 1/2 of the work per hour.
Now, what would be the rate of work if they were working together? Let's look at it like this:
Hours to complete the job:
Tiana = 3
Jacob = 2
Together = t
Work done per hour:
Tiana = 1/3
Jacob = 1/2
Together = 1/t
If you add their labor together:
1/3 + 1/2 = 1/t
5/6 = 1/t
t = 6/2 = 1.2
Together, they can clear the field in 1.2 hours.
I don’t really understand your question can you go into detail more please
6xY + 6x7= 6y+42
2xY - 2x3= 2y-6
6y+42=2y-6 solve for y...
y= -12