Hey!
You have to find 80% of 70. First change 80% to a decimal and multiply by 70.
To change percents to decimals, remove the % sign and move the decimal point 2 places to the left.
[tex] 80 \% \rightarrow 0.8 [/tex]
Now multiply
[tex] 0.8 \times 70 = 56 [/tex]
The restaurant sold 56 salmon fillets.
Good luck and hope this helps! :)