Step-by-step explanation:
If [tex]mKg[/tex] of mass is placed on spring with spring constant [tex]k[/tex],
[tex]mg=kx[/tex]
where [tex]g[/tex] is universal gravitational constant
[tex]x[/tex] is the displacement in the spring.
In case 1:
[tex]25g=k(0.15)\\k=\frac{25g}{0.15}[/tex]
In case 2:
[tex]mg=k(0.23)[/tex]
Using result from case 1,
[tex]mg=\frac{25g}{0.15}\times 0.23[/tex]
[tex]m=[/tex][tex]38.33Kg[/tex]