Answer:
Interest earned will be $8.40 over 6 months.
Explanation:
Step 1 - let's find out how much interest is earned over 1 year:
($840/100) * 2 = $16.8 - this is how much Marc would've earned over one year if he meets all criterias (No further deposits or withdrawals)
Step 2 - let's find out what would've been his interest in one month:
$16.8 / 12 = $1.4 - this is how much would've he earned per month.
Step 3 - let's find out how much he would've earned on 6 months:
$1.4 * 6 = $ 8.4. Rounded to nearest cent: $8.40