During the sale, the stereo system was sold for 30% less than its original price of $710, so the discount amount was:
0.30 x $710 = $213
Therefore, the sale price of the stereo system was:
$710 - $213 = $497
After the sale, the discounted price of $497 was marked up by 30%. The markup amount is:
0.30 x $497 = $149.10
So the final price of the stereo system after the markup is:
$497 + $149.10 = $646.10
Therefore, the price of the stereo system after the markup is $646.10.