$29.74
Step 1: finding the 21% of $24.58
In order to find the percentage of any quantity, we just divide the percentage by 100:
[tex]\frac{21}{100}=0.21[/tex]and then we multiply it by the quantity, in this case the total value is $24.58:
[tex]0.21\cdot24.58=5.16[/tex]Then, the 21% of $24.58 is $5.16.
Step 2: adding the result to the bill
He should pay the bill, $24.58 and the tip, $5.16, then, he must pay:
$24.58 + $5.16 =$29.74
That is why the answer is $29.74.