\[\boxed{\text{655\ (655).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[\textbf{а)}\ 5x + 5y = 5 \cdot (x + y)\]
\[\textbf{б)}\ 4a - 4b = 4 \cdot (a - b)\]
\[\textbf{в)}\ 3c + 15d = 3 \cdot (c + 5d)\]
\[\textbf{г)} - 6m - 9n = - 3 \cdot (2m + 3n)\]
\[\textbf{д)}\ ax + ay = a \cdot (x + y)\]
\[\textbf{е)}\ bc - bd = b \cdot (c - d)\]
\[\textbf{ж)}\ ab + a = a \cdot (b + 1)\]
\[\textbf{з)}\ cy - c = c \cdot (y - 1)\]
\[\textbf{и)} - ma - a = - a(m + 1)\ \]