Simplify 3/4 * (2 1/2 - 4/5).

$$3 \frac{1}{4} = \frac{(3 \times 4) + 1}{4} = \frac{12 + 1}{4} = \frac{13}{4}$$ $$2 \frac{1}{2} = \frac{(2 \times 2) + 1}{2} = \frac{4 + 1}{2} = \frac{5}{2}$$

$$\left(\frac{5}{2} - \frac{4}{5}\right)$$

To subtract these fractions, find a common denominator, which is 10.

$$\frac{5}{2} = \frac{5 \times 5}{2 \times 5} = \frac{25}{10}$$ $$\frac{4}{5} = \frac{4 \times 2}{5 \times 2} = \frac{8}{10}$$

Now subtract:

$$\frac{25}{10} - \frac{8}{10} = \frac{25 - 8}{10} = \frac{17}{10}$$

$$\frac{13}{4} \times \frac{17}{10}$$

Multiply the numerators and the denominators:

$$\frac{13 \times 17}{4 \times 10} = \frac{221}{40}$$

$$\frac{221}{40} = 5 \frac{21}{40}$$

The simplified expression is:

$$\frac{221}{40} \text{ or } 5 \frac{21}{40}$$