Simplify: (cd-c /(d-c) 2 2/(3a)+5/(2b) xcyz2/(abcxyz) Write in standard fo 368 0.00006784 0.00321 458754

$$\frac{c}{d-c}$$

The simplified expression is $\boxed{\frac{c}{d-c}}$.

b) $\frac{2}{3a} + \frac{5}{2b}$

$$\frac{2 \cdot (2b)}{3a \cdot (2b)} + \frac{5 \cdot (3a)}{2b \cdot (3a)}$$ $$\frac{4b}{6ab} + \frac{15a}{6ab}$$

$$\frac{4b+15a}{6ab}$$

The simplified expression is $\boxed{\frac{4b+15a}{6ab}}$.

c) $\frac{xcyz^2}{abcxyz}$

$$\frac{z}{ab}$$

The simplified expression is $\boxed{\frac{z}{ab}}$.

5. Write in standard form:

Standard form (scientific notation) is written as $a \times 10^n$, where $1 \le |a| < 10$ and $n$ is an integer.

a) 368

Since it was moved 2 places to the left, the exponent of 10 is 2.

$$3.68 \times 10^2$$

The standard form is $\boxed{3.68 \times 10^2}$.

b) 0.00006784

Since it was moved 5 places to the right, the exponent of 10 is -5.

$$6.784 \times 10^{-5}$$

The standard form is $\boxed{6.784 \times 10^{-5}}$.

c) 0.00321

Since it was moved 3 places to the right, the exponent of 10 is -3.

$$3.21 \times 10^{-3}$$

The standard form is $\boxed{3.21 \times 10^{-3}}$.

d) 458754

Since it was moved 5 places to the left, the exponent of 10 is 5.

$$4.58754 \times 10^5$$

The standard form is $\boxed{4.58754 \times 10^5}$.