彼(かれ)の考(かんが)えは私(わたし)の考(かんが)えと真逆(まぎゃく)です。

His opinion is the exact opposite of mine.

私(わたし)の予想(よそう)とは真逆(まぎゃく)の結果(けっか)になった。

The result was the exact opposite of what I expected.

姉(あね)は静(しず)かな性格(せいかく)だが、弟(おとうと)は真逆(まぎゃく)でとても活発(かっぱつ)だ。

My older sister has a quiet personality, but my younger brother is the exact opposite and very active.