Answer
$P(\frac{4}{5},\frac{-3}{5})$
Work Step by Step
We have the following equation for the unit circle:
$x^{2}+y^{2}=1$, so we plug in $P(x,\frac{-3}{5})$,
$x^{2}+({\frac{-3}{5}})^{2}=1$
$ y^{2}=1 - \frac{9}{25}= \frac{16}{25}$
$y = \frac{4}{5}$ or $y = - \frac{4}{5}$ but the x-coordinate is positive so $x = \frac{4}{5}$
