Correct answer: 3
The electric flux through a surface is given by the product of the electric field and the area of the surface projected in the direction of the field. For the rectangular surface parallel to the y-z plane, the area is 0.2 m² and the electric field has a component of rac{4}{5} N/C in the j direction, resulting in a flux of 0.2 * rac{4}{5} = 0.16 N·m²/C. For the surface parallel to the x-z plane, the area is 0.3 m² and the electric field has a component of rac{3}{5} N/C in the i direction, resulting in a flux of 0.3 * rac{3}{5} = 0.18 N·m²/C. The ratio of these two fluxes is 0.16:0.18, which simplifies to 3:5, thus a = 3.