Solution

Observe the last row:

$9,\ 6,\ 5,\ 5$

Using the row-wise relation,

$\text{Required number}=(\text{first number}\times \text{third number})-(\text{second number}+\text{fourth number})$

So,

$?=(9\times 5)-(6+5)$

$?=45-11$

$?=34$