{m_3}{e^{ - i{\phi _3}}} &=& \frac{1}{{c_{13}^2}}\left[ {a_ + ^2 + b_ + ^2 - s_{13}^2t_{12}^2\left( {a_ - ^2 + b_ - ^2} \right){e^{ - 2i{\delta _{CP}}}}} \right].
\label{Eq:masses for NHseesaw}\end{aligned}$$ For IH, we have $m_3=0$ leading to $$a_ + ^2 + b_ + ^2 = t_{13}^2\left( {a_1^2 + b_1^2} \right){e^{ - 2i{\delta _{CP}}}},
\label{Eq:m3=0 for seesaw}$$ and obtain that $$\begin{aligned}
&&
{a_ + }{a_ - } + {b_ + }{b_ - } =  - {t_{13}}\left( {{a_1}{a_ - } + {b_1}{b_ - }} \right){e^{ - i{\delta _{CP}}}},
\label{Eq:23 for IHseesaw}\\
&&
\sin 2{\theta _{12}}\left( {\frac{{a_1^2 + b_1^2}}{{c_{13}^2}} - \left( {a_ - ^2 + b_ - ^2} \right)} \right) =  - 2\cos 2{\theta _{12}}\frac{{{a_1}{a_ - } + {b_1}{b_ - }}}{{{c_{13}}}},
\label{Eq:12 for IHseesaw}\\
&&
{a_1}{a_ + } + {b_1}{b_ + } =  - {t_{13}}\left( {a_1^2 + b_1^2} \right){e^{ - i{\delta _{CP}}}},
\label{Eq:13 for IHseesaw}\end{aligned}$$ and $$\begin{aligned}
{m_1}{e^{ - i{\phi _1}}} &=& a_ - ^2 + b_ - ^2 - \frac{{{a_1}{a_ - } + {b_1}{b_ - }}}{{{t_{12}}{c_{13}}}},
\nonumber\\
{m_2}{e^{ - i{\phi _2}}} &=& a_ - ^2 + b_ - ^2 + \frac{{{t_{12}}}}{{{c_{13}}}}\left( {{a_1}{a_ - } + {b_1}{b_ - }} \right).
\label{Eq:masses for IHseesaw}\end{aligned}$$ We would like to obtain simple solutions to these equations 