Dielectric Constant Calculation: 110 & 240 µC

[wadini]

When a certain air filled parallel plate capacitor is connected cross a battery, it acquires a charge (on each plate) of 110 micro Columbs. While the battery connection is maintained, a dielectric slab is inserted into and fills the region between the plates. This results in the accumulation of an additional charge of 240 micro Columbs on each plate.

What is the dielectric constant of the dielectric slab?

so I have Q1=110 micro Columbs and Q2= 240 micro Columbs;E= 8.85419e-12 C^2/N*m^2; and Air= 1.00054 which is believe is K1

I just don't know what equation to use or how to go about this problem in general.

 

[rl.bhat]

What is the relation between C, V and Q.
In the problem which quantity remains constant in both the cases?
Write down two equations for two cases and then solve for K.