I need to use simple formula I = Prt and elementary algebra to find the missing quantities in this table.

Using the formula I = Prt with the given values of I, P and r, let's calculate the value of t.
We need to remember that the percentage value r = 6% is equivalent to r = 0.06.
So we have:
[tex]\begin{gathered} I=P\cdot r\cdot t\\ \\ 3696=8800\cdot0.06\cdot t\\ \\ 3696=528\cdot t\\ \\ t=\frac{3696}{528}\\ \\ t=7 \end{gathered}[/tex]Therefore the answer is t = 7 years.