Answer
$\$ 1250$.
Work Step by Step
The year-after-year values of the computer form an arithmetic sequence with
$a=12,500$ and common difference $d=-1875$.
After six years, $\$ 1875$ has been subtracted 6 times, so we are after the term $a_{7}$!
$a, a+d, a+2d, a+3d, ... ,a+6d.$
$a_{n}=a+(n-1)d$
$a_{7}=12,500+(7-1)(-1875)=\$ 1250$.
The value of the computer after 6 years is $\$ 1250$.
