tolong dijawab yah !!!

k = F / Δx
   = 20 N / (0,4 m) = 50 N/m

EP = 1/2 kΔx²
      = 1/2 (50 N/m)(0,4 m)² = 4 J
atau
EP = 1/2 FΔx
      = 1/2 (20 N)(0,4 m) = 4 J
Jawaban: E.