Solution to Problem 641 | Deflection of Cantilever Beams

$\dfrac{1}{EI}(Area_{AC}) \, \bar{X}_A = 0$

$\dfrac{1}{EI} [ \, \frac{1}{2}(4)(4P)(\frac{8}{3}) - 2(400)(3)\, ] = 0$

$P = 112.5 \, \text{ N}$           answer