In a rectangle, the length of the diagonals are equal. Hence, we can set \( AO \) equal to \( BO \):
\[ 4x - 3 = 5x - 10 \]
To solve for \( x \), we first rearrange the equation:
\[ 4x - 5x = -10 + 3 \]
This simplifies to:
\[ -x = -7 \]
Multiplying both sides by -1 gives us:
\[ x = 7 \]
So, the value of \( x \) is \( 7 \).
The answer is \( x = 7 \).