A series LCR circuit consists of R = 80   Ω . X L = 100   Ω , and X C = 40  …

Comparing input voltage with standard expression, $V=V_0\cos \left(\omega t\right)$, we get $\omega =100\pi$.

Now, impedance $Z=\sqrt{R^2+{\left(X_L-X_C\right)}^2}$

$=\sqrt{{80}^2+{\left(100-40\right)}^2}$

$=100\mathrm{\Omega }$

Therefore, peak current

$i_0=\frac{V_0}{Z}=\frac{2500}{100} \mathrm{A}=25 \mathrm{A}$