Solve for the unknown number of years in each of the following: $($Do not round intermediate calculations and round your answers to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

$\backslash$table$[[$Present Value,Years,Interest Rate,Future Value$],[$$$,8,\%,$$$,1,075],[750,,12,\%,1,836],[17,800,,18,\%,294,671],[20,900,,14,\%,320,610]]$