\[\boxed{\mathbf{287\ (287)}.\ Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\angle ENM;\ \ \angle ENC;\ \angle ENA;\ \ \angle ANC;\ \]
\[\ \angle ANM;\ \ \angle CNM.\]
\[\boxed{\mathbf{287}\mathbf{\ (251)}.\ Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ (238 + 416) - 519 = 135\]
\[2)\ (823 - 374) + (3477 - 3086) =\]
\[= 840\]
\[3)\ (15 + 12) \cdot (15 - 12) =\]
\[= 27 \cdot 3 = 81\]
\[4)\ (209 + 193)\ :(42\ 930 - 42\ 924) =\]
\[= 67\]