Fix cw.tex

cw/cw.tex

@@ -144,9 +144,21 @@
 	\end{cases}
 	$$	
 
-	$$v=77(137,312) + 93(215,-187)=(30544, 6633)$$
+	$$v'=77(137,312) + 93(215,-187)=(30544, 6633)$$
-	$$r=w-v=(4, 9)$$
+	$$r=w-v'=(4, 9)$$
 
+	$$
+	w = v'\times m + r\iff
+		m= (30544, 6633)\times\begin{pmatrix}
+			1975 & 438\\
+			7548 & 1627\\
+		\end{pmatrix}^-1}\iff
+		m=(4,3)
+	$$
+	
+	The plaintext is $(4, 3)$ and the $r=(4,9)$
+
+	C:
 
 	\subsection*{7.2}
 	No he should not.