Answer: $840 was the interest
Step-by-step explanation:
Simple interest formula:
[tex]Final = Initial Balance * (1+(interest * time))[/tex]
Where time is in years
[tex]8000 * (1+(\frac{7}{100} *\frac{18}{12})) = 8840[/tex]
$8840 - 8000 = 840 interest was gained
