We could distribute first, but it will get a bit messy.
$$ -\frac{1}{3}\left(x-\frac{8}{3}x\right)=-5 $$
$$ -\frac{1}{3}x+\frac{8}{9}x=-5$$
Depending on how you like to deal with fractions,
Fraction arithmetic
$$ -\frac{1}{3}x+\frac{8}{9}x=-5$$
$$-\frac{3}{9}x+\frac{8}{9}x=-5$$
$$\frac{5}{9}x=-5$$
$$x=-5\left(\frac{9}{5}\right) $$
Multiply each term by the least common denominator
$$ -\frac{1}{3}x+\frac{8}{9}x=-5$$
$$\left(9\right)\left(-\frac{1}{3}x+\frac{8}{9}x\right)=\left(-5\right)\left(9\right)$$
$$ -3x+8x=-45$$
$$ 5x=-45$$
$$ x=-\frac{45}{5} $$
$$x=\boxed{-9}$$
Deal with the outer fractional coefficient first by multiplying both sides by \(-3\).
$$ -\frac{1}{3}\left(x-\frac{8}{3}x\right)=-5 $$
$$ (-3)\left(-\frac{1}{3}\left(x-\frac{8}{3}x\right)\right)=(-5)(-3) $$
$$ x-\frac{8}{3}x=15 $$
Again, we have two choices for how to deal with these types of equations.
Fraction arithmetic
$$ x-\frac{8}{3}x=15 $$
$$ \frac{3}{3}x-\frac{8}{3}x=15 $$
$$ -\frac{5}{3}x=15$$
$$ x=15 \left(-\frac{3}{5}\right) $$
Multiply each term by the least common denominator
$$ x-\frac{8}{3}x=15 $$
$$ (3)\left(x-\frac{8}{3}x\right)=15(3) $$
$$ 3x-8x=45$$
$$-5x=45$$
$$x=-\frac{45}{5}$$
$$ x=\boxed{-9}$$