This problem was given with a graph showing that when the spring was elongated to 7 m, the force was approximately 11 N. Seeing as the EPE is calculated by finding the area under the graph and that the area of a triangle is found by using A = 1/2bh, you can see that the givens are b = 7 m & h = 11 N. This means that the the EPE = 1/2 * 7 m * 11 N, which is 38.5N*m. Joules are also represented by N*m so that simplifies to J and seeing as they asked for an approximation, C is the best choice! :)
