mohon bantuannya terutama nomor 3 dan 4. please help me?

3. γ = 4 x 10^6 N/m²
A = 20 cm² = 20 x 10^-4 m²
ι = 5 m

γ = σ/ε = (F ι) / (A Δι)
F = (γAΔι )/ ι

maka konstanta gaya logamnya
k = γA/ι = (4 x 10^6 x 20 x 10^-4)/5
k = 16 x 10² = 1600 N/m

4. k1 = 40 N/m
k2 = 60 N/m
disusun paralel, maka konstanta pegas totalnya
k = k1 + k2 = 100 N/m

F = kx
gaya disebabkan oleh gaya berat
F = w = mg = kx
2 (10) = 100 x
x = 20/100 = 0.2 m = 20 cm