Question

F= m delta v/ delta t. How do I solve for "t"?

Answer 1

By you writing delta I'll assume you don't use derivatives yet. This is how I would do it \[F=\frac{ \Delta v }{ \Delta t }*m =\frac{ v _{2}-v _{1} }{ t _{2} - t _{1}}*m, t _{1}=0 \]
t1 is zero because you always start counting from zero, you don't start your stopwatch at 5 seconds for example
\[t _{2}*F= (v _{2}-v _{1})*m \rightarrow t _{2}=\frac{ (v _{2}-v _{1})*m }{F }\]