If (2a-b)/(6a-5b) = -3, find 5a:2b.

We are given the equation:

$$\frac{2a-b}{6a-5b} = -3$$

Multiply both sides by $(6a-5b)$:

$$2a-b = -3(6a-5b)$$

Distribute the $-3$ on the right side:

$$2a-b = -18a + 15b$$

Add $18a$ to both sides:

$$2a + 18a - b = 15b$$ $$20a - b = 15b$$

Add $b$ to both sides:

$$20a = 15b + b$$ $$20a = 16b$$

Divide both sides by $b$ and by 20:

$$\frac{a}{b} = \frac{16}{20}$$

Simplify the fraction by dividing the numerator and denominator by their greatest common divisor, which is 4:

$$\frac{a}{b} = \frac{16 \div 4}{20 \div 4} = \frac{4}{5}$$

So, the ratio $a:b$ is $4:5$.

We need to find the value of $\frac{5a}{2b}$. We can rewrite this as:

$$\frac{5a}{2b} = \frac{5}{2} \times \frac{a}{b}$$

Substitute the value of $\frac{a}{b}$ from Step 3:

$$\frac{5a}{2b} = \frac{5}{2} \times \frac{4}{5}$$

Multiply the fractions:

$$\frac{5a}{2b} = \frac{5 \times 4}{2 \times 5} = \frac{20}{10}$$ $$\frac{5a}{2b} = 2$$

This means the ratio $5a:2b$ is $2:1$.

The final answer is $\text{C) 2 : 1}$.