Question 826490
"Simple Interest", as in "no compounding".  Rate assumed "per year".


year count_______________money result
1________________________1800+0.04(1800)
2________________________1800+2(0.04)(1800)
3________________________1800+3(0.04)(1800)
.
x________________________1800+x*(0.04)(1800)


Your question asks, what is x in {{{1800+(0.04)*1800x=2500}}} ?
{{{(0.04)1800x=700}}}
{{{highlight(x=(700)/(0.04*(1800)))}}}


Would 9 years be enough?  No.  Need full 10 years, but this would yield a bit more than 2500 dollars balance.  Could the yearly earning be pro-rated?  That would help.