Given:-
The simple interest earned is $378 the principal is $450 and interest rate is 12%.
To find:-
The time.
So the formula is,
[tex]Time=\frac{100\times Intrest}{Pri\text{ ncipal}\times Rate}[/tex]Substituting the value we get,
[tex]T=\frac{100\times378}{450\times12}[/tex]So by simplifying we get,
[tex]\begin{gathered} T=\frac{37800}{450\times12} \\ T=\frac{37800}{5400} \\ T=7 \end{gathered}[/tex]So the required solution is 7 years.