In ths case the answer is very simple.
Step 01:
Data:
p = investment = $217
r = interest rate = 6% = 0.06
I = interest = $78.12
t ( years) = Time = ?
Step 02:
Simple Interest
I = p * r * t
78.12 = 217 * 0.06 * t
[tex]\begin{gathered} \frac{78.12}{217\cdot0.06}=t \\ 6\text{ = t} \end{gathered}[/tex]The answer is:
t = 6 years
