A box of mass M is kept on a frictionless and inclined plane which is inclined at an angle $\text{θ}$  with the horizontal. A box is having another frictionless inclined plane, inclined at same angle $\text{θ}$ with the previously described inclined plane as shown in the figure. If a block of mass m is kept on this inclined plane inside the box, then

the acceleration of the block with respect to the box is $\frac{\left(\text{M+m}\right)\text{gsinθcosθ}}{{\text{M+msin}}^{\text{2}}\text{θ}}$  towards the left side.

the acceleration of the block with respect to the box is $\frac{\left(\text{M+m}\right)\text{gsinθcosθ}}{{\text{M+msin}}^{\text{2}}\text{θ}}$ towards the right side.

the normal reaction between the box and the inclined plane is  $\frac{m\left(\text{M+m}\right)\text{gcosθ}}{{\text{M+msin}}^{\text{2}}\text{θ}}$

the normal reaction between the box and the block is  $\frac{Mm{\text{gcos}}^2\text{θ}}{{\text{M+msin}}^{\text{2}}\text{θ}}$