A block is simply released from the top of an inclined plane as shown in the figure above. The maximum compression in the spring when the block hits the spring is :

The kinetic energy at bottom is the potential energy when it was at the top of inclined plane

$$W_{KE}$$= mgh

=$$5 \times 10 \times (10\sin30^\circ)$$

=$$250\text{ J} $$

Friction acts opposite to the motion of block,so this is negative work

$$W_{fr} $$=$$ \mu mgd $$

=$$ 0.5 \times 5 \times 10 \times 2 $$

=$$ 50\text{ J}$$

the leftover energy now, is stored completely in spring as final kinetic energy of mass is 0.

$$W_{spring} $$= $$\frac{1}{2}(100)x^2 $$=$$ 50x^2 $$

250 - 50 = $$50x^2 $$

200=$$50x^2 $$

4=$$x^2 $$

$$x$$=2