Evaluate the expression 1 2/3 - 1 2/3 x 1/4 and solve the equation 5x - 8 - 3(x + 1) = -7.

$$1\frac{2}{3} - 1\frac{2}{3} \times \frac{1}{4} = \frac{5}{3} - \frac{5}{3} \times \frac{1}{4}$$ $$= \frac{5}{3} - \frac{5 \times 1}{3 \times 4}$$ $$= \frac{5}{3} - \frac{5}{12}$$

The common denominator for 3 and 12 is 12.

$$= \frac{5 \times 4}{3 \times 4} - \frac{5}{12}$$ $$= \frac{20}{12} - \frac{5}{12}$$ $$= \frac{20 - 5}{12}$$ $$= \frac{15}{12}$$

$$= \frac{5}{4}$$ $$= 1\frac{1}{4}$$

The final answer is $\boxed{\text{1}\frac{1}{4}}$ or $\boxed{\text{1.25}}$.

$$5x - 8 - 3(x + 1) = -7$$ $$5x - 8 - 3x - 3 = -7$$

$$(5x - 3x) + (-8 - 3) = -7$$ $$2x - 11 = -7$$

$$2x - 11 + 11 = -7 + 11$$ $$2x = 4$$

$$\frac{2x}{2} = \frac{4}{2}$$ $$x = 2$$

The final answer is $\boxed{\text{x = 2}}$.

$$5(2y - 3) - 2(5 - 2y)$$ $$= (5 \times 2y) + (5 \times -3) + (-2 \times 5) + (-2 \times -2y)$$ $$= 10y - 15 - 10 + 4y$$

$$(10y + 4y) + (-15 - 10)$$ $$= 14y - 25$$

The final answer is $\boxed{\text{14y - 25}}$.

Total capacity = 512 units.
Fraction used = $\frac{2}{3}$.
Memory used = $\frac{2}{3} \times 512$ units

$$= \frac{1024}{3} \text{ units}$$ $$= 341.333... \text{ units}$$

Unused units = Total capacity - Memory used

$$= 512 - \frac{1024}{3}$$ $$= \frac{512 \times 3}{3} - \frac{1024}{3}$$ $$= \frac{1536}{3} - \frac{1024}{3}$$ $$= \frac{1536 - 1024}{3}$$ $$= \frac{512}{3} \text{ units}$$

$$= 170.666... \text{ units}$$

Rounding to 2 decimal places, we get 170.67 units.
The final answer is $\boxed{\text{170.67 units}}$.