Answer
The positive values are $0\lt x\leq3.3$.
Work Step by Step
Perimeter is
$=x+4.1+4.9+6.4$
The inequality is
Perimeter $\leq18.7$
$\Rightarrow x+4.1+4.9+6.4\leq18.7$
Add like terms.
$\Rightarrow x+15.4\leq18.7$
Subtract $15.4$ from each side.
$\Rightarrow x+15.4-15.4\leq18.7-15.4$
Simplify.
$\Rightarrow x\leq3.3$
Side must be greater than zero.
Hence, the positive values are $0\lt x\leq3.3$.
