Solution

The root node is a $MAX$ node.

In minimax method:

$MAX$ node selects the maximum value from its children.

$MIN$ node selects the minimum value from its children.

From the left subtree, the minimum level gives values such that the final value of the left side becomes

$7$

From the right subtree, the available minimum values make the right side value less than or equal to $5$.

Now, root is a $MAX$ node, so it selects maximum of left and right subtree values.

$\max(7,\le 5)=7$

Hence, the value of the root node is

$7$