$${\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{5}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{5}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5}}{\mathtt{\,-\,}}{\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{5}} = {\mathtt{30}}$$
PEMDAS
5*5 = 25
25 + 25 + 5 - 25 = n
50 + 5 - 25 = n
55 - 25 = n
30 = n
Your answer is 30.
(Also, this answer puts me into the Top Answerers list! Yay!)