The Work Done on an Object, in Joules, Is Equal $F$

The work done on an object, in joules, is equal to the area under the curve on the graph below of the force $F$ on the object vs the distance $x$ over which $F$ is applied to the object. For an object on the end of a spring with a force constant of $2 \mathrm{~N} / \mathrm{m}$ , the force of the spring on the object is given by $F=-2 x \mathrm{~N}$ . Find the work done by the spring when $x$ goes from $-3 \mathrm{~m}$ to $0 \mathrm{~m}$ .