Answer:
$16.62 each
Explanation:
First, find 20% of the bill to figure out how much the tip is worth:
20% over 100% = $x over $55.40 ---> 20 * 55.4 / 100 = 11.08
Now that we know the tip is $11.08, next add it on to the bill:
$11.08 + $55.40 = $66.48
Now divide this by 4 to split the bill evenly between the 4 friends:
$66.48 / 4 = $16.62