Let when the combination of springs is compressed by force $\mathrm{F}$. Spring $A$ is compressed by $x$. Therefore compression in spring $\mathrm{B}$
$x_{B}=(8.75-x) c m$
$\mathrm{F}=300 \times x=400(8.75-x)$
Solving we get, $x=5 \mathrm{cm}$
$x_{B}=8.75-5=3.75 \mathrm{cm}$
$\frac{E_{A}}{E_{B}}=\frac{\frac{1}{2} k_{A}\left(x_{A}\right)^{2}}{\frac{1}{2} k_{B}\left(x_{B}\right)^{2}}=\frac{300 \times(5)^{2}}{400 \times(3.75)^{2}}=\frac{4}{3}$

