#### Answer

$0.85x$.

#### Work Step by Step

Since the original price of the computer is $x$, a $15$% reduction implies subtracting the $15$% of the original price ($0.15x$). This can be written in the following manner: $$x - 0.15x$$ However, since both terms of the expression share a variable, we can further simplify it by continuing the subtraction: $$1x - 0.15x = 0.85x$$ The final, correct expression is $0.85x$.