Step 1: Find the sales price
The surfboard was marked down 40% of its original price, $521.28.
0.40(521.28) = 208.512
521.28 - 208.512 = 312.768
Step 2: Find the final price
We add the tax on the sales price, not the original price. The tax is 10% in this case.
0.10(312.768) = 31.2768
312.768 + 31.2768 = 344.0448
Final price = $344.04
---I did not round until the end in this case, but rounding at every step leads to an answer of $344.05
Hope this helps!