help me in this chemistry MCQ

[bionology]

i have seen many questions on this pattern but seriously i failed to work out how do we get the answer
anyone here if explains this, would be of great help

The question states that the pressure of a 5dm^3 helium vessel (X) is 12KPa, and that of 10dm^3 neon vessel (Y) is 6KPa, if both are mixed together, what will be the final pressure of the vessel?
a. 8KPa
b. 9KPa
c. 10KPa
d. 11KPa

For your convenience the answer is 8KPa, (A), i need to know the process followed to reach the answer

 

[Xthegreat]

when 2 vessel joins together, the total volume becomes 15dm3

using p1v1= p2v2
for vessel X
- 5 x 12 = p x 15
- p = 4kPa
for vessel Y
- 10 x 6 = p x 15
- p = 4kPa
hence total P is 4 + 4 = 8

 

[princesszahra]

when 2 vessel joins together, the total volume becomes 15dm3

using p1v1= p2v2
for vessel X
- 5 x 12 = p x 15
- p = 4kPa
for vessel Y
- 10 x 6 = p x 15
- p = 4kPa
hence total P is 4 + 4 = 8

corret!

 

[bionology]

oh thankyou so much, I used to get that 4KPa only, once again, thanks alot