Answer:
$8.4
Explanation:
To find how much money you should leave for a tip, we need to find how much is 20% of $42. So, to calculate this, we need to multiply 42 by 20 and then divide by 100, so:
$42 x 20% = 42 x 20 / 100 = 840 / 100 = 8.4
Therefore, the answer is $8.4