40% off the regular price is better because:
Let's say the surfboard is $50. 40% off $50 means you are paying:
50 x 0.6 = $30.
30% off $50 means you are paying:
50 x 0.7 = $35.
Then 10% off $35 means you are paying:
$35 x 0.9 = $31.50.
Therefore, it is cheaper to get 40% off the surfboard
