Answer:
200
Step-by-step explanation:
Janet = x + 75
Kathy = x
2x + 75 = 325
2x = 325 - 75
2x = 250
x/Kathy = 125
x + 75/Janet = 125 + 75
= 200
Answer: Approximately 1.9 atm
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Work Shown:

If the volume is 3.5 liters, then the pressure is approximately 1.9 atm.
Note the increase in volume leads to the reduction of pressure, and vice versa. The two variables have an inverse relationship.
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As a check,

We don't get the exact thing on both sides, but the two sides are close enough. We have rounding error due to P2 being not exact.
A more accurate check could be

which has the two sides much closer to one another. This helps us verify the answer.
Given the ratio, you know that:
length = 6x
width = 2x
height = 7x
Because the sum of the length and the width is 24 cm, you can write the equation:
6x + 2x = 24
Solve:
8x = 24
x = 3
Plug the 3 back into the expressions written earlier for length, width, and height.
length = 18 cm
width = 6 cm
height = 21 cm
Use the formula SA = 2B + Ph to solve for the surface area.
Surface Area = 2(area of the base) + (perimeter of the base)(height)
I'm going to plug in l, w, and h as variables for length, width, and height to show the exact way to solve for the B and P.
SA = 2lw + 2(l + w)h
SA = 2(18)(6) + 2(18 + 6)(21)
SA = 216 + 2(24)(21)
SA = 216 + 1008
SA = 1224
The surface area is 1,224 cm^2.
Continuous, because its the area.
Hope this helps...