Work on a spring

First figure gives spring force $F_{x}$ versus position x for the spring-block arrangement of second figure. The scale is set by $F_{s} = 160N$ . This relation holds up to x =± 20 cm. We release the block at x = 12 cm. The mass of the block is 2 kg and the friction between the block and the floor is negligible.

Q : How much work does the spring do on the block when the block moves from $x_{i}$ = +8 cm to -10 cm?