Question 1178692
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The original amount earns the 7.05% annual interest for the full 11 years; the additional amount x earns it for 8 years.<br>
I will assume compound interest, since no savings institution today pays simple interest.  So<br>
{{{1140(1.0705)^11+x(1.0705)^8 = 8200}}}
{{{2481.89+1.72462x = 8200}}}<br>
You can finish.  Use a calculator....<br>