Question

3+7x4[45-3x(4xa+3)]=3

Answer 1

$\it 3+7\times4[45-3\times(4\times a+3)]=3\Big|_{_{-3}} \Rightarrow 28[45-3\times(4\times a+3)]=0\Big|_{:28} \Rightarrow\\ \\ \Rightarrow 45-3\times(4\times a+3)=0 \Rightarrow 3\times(4\times a+3)=45\Big|_{:3} \Rightarrow 4\times a+3=15\Big|_{-3} \Rightarrow\\ \\ \Rightarrow 4\times a=12\Rightarrow \Big|_{:4} \Rightarrow a=3$