24. Electric Force & Field; Gauss' Law

A $4.0\mathrm{cm}\times 5.0\mathrm{cm}$ rectangle lies in the x-y plane; let the normal vector point in the z direction. What is the flux through the rectangle of a uniform electric field $\stackrel{\rightharpoonup }{E}=(-7.8\times {10}^5\widehat{j}+2.3\times 10^5\widehat{k})N/C$

A uniform electric field points in the positive x direction and has a magnitude of $40\mathrm{N}/\mathrm{C}$. What is the total flux through a rectangle with height $20\mathrm{cm}$ and width $45\mathrm{cm}$? The rectangle lies in the y-z plane.