Expressions · Superchallenge problem

The whole numbers $1$ to $100$ are written in a chart with $10$ numbers in each row: $1$ to $10$ in the first row, $11$ to $20$ in the second, and so on. A T-shaped piece covers exactly five numbers: three side by side in one row, and the two numbers directly below the middle one of those three (one in each of the next two rows). The five covered numbers add up to $325$. What is the largest covered number?