Question 149841
The formula is
{{{A = P*(1 + tr)}}}
Principle = {{{P}}}
number of years = {{{t}}}
Amount paid on loan after {{{t}}} years = {{{A}}}
Annual interest rate  = {{{r}}}
Interest after {{{t}}} years = {{{A - P}}}
------------------
Given is {{{r = .035}}}
{{{A - P = 245}}}
{{{t = 3.5}}}
------------------
{{{P = A - 245}}}
{{{A = P*(1 + tr)}}}
{{{A = (A - 245)*(1 + tr)}}}
{{{A = (A - 245)*(1 + 3.5*.035)}}}
{{{A = (A - 245)*1.1225}}}
{{{A = 1.1225A - 275.0125}}}
{{{.1225A = 275.0125}}}
{{{A = 2245}}}
{{{P = A - 245}}}
{{{P = 2245 - 245}}}
{{{P = 2000}}} 
The principle was $2000 answer
plug this back into formula to check
{{{A = P*(1 + tr)}}}
{{{2245 = 2000*(1 + 3.5*.035)}}}
{{{2245 = 2000*1.1225}}}
{{{2245 = 2245}}}
OK