Answer
$8 \space hours$
Work Step by Step
As we know Speed = distance $\div$ time
$Speed = (300) \div (6)$
$Speed =50 \space mph$
New speed becomes: $50 +5 =55$ mph
The time taken let us say $T$by Sandra with this new speed can be calculated as:
$T= \dfrac{440}{55}$
$T =8 \space hours$
