E=(53E0i^+54E0j^)NC−1
A1=0.2m2 [parallel to y−z plane]
=A1=0.2m2i^
A2=0.3m2 [parallel to x−z plane]
A2=0.3m2j^
Now, ϕa=[53E0i^+54E0j^]⋅[0.2i^]=53×0.2E0
&{\phi }_{b}=[\frac{3{E}_{0}}{5}\hat{i}+\frac{4{E}_{0}}{5}\hat{j}]\cdot [0.3\hat{j}]=\frac{4\times 0.3}{5}{E}_{0}
Now, ϕbϕa=1.20.6=21=ba
⇒a:b=1:2
⇒a=1