Modulation co-efficient (m) = $\frac{V_{max} - V_{min}}{V_{max} + V_{min}}$

$= \frac{20-41}{20+4}$

$= \frac{16}{24}$

m = 0.66

$V_m$ (modulating voltage) = E $\frac{V_{max}-V_{min}}{2}$

$= \frac{20-4}{2}$

= 16/2

$V_m = 8V$

Peak amplitude of carrier $V_c = V_{max} - V_m $

= 20-8V

$V_c = 12V$

Peak amplitude of VSF-LSF = $\frac{mvc}{2}$

$= 0.66 \times \frac{12}{2}$

$V_{VSF}$ & $V_{LSF} = 3.96 \ V$