Simplify the numerator

First, evaluate the expression inside the brackets: $150 - 30 = 120$ and $30 \div 2 = 15$. Then divide: $120 \div 15 = 8$. Finally, add and subtract: $8 - 10 + 5 = 3$.

$(150 - 30) \div (30 \div 2) - 10 + 5 = 120 \div 15 - 10 + 5 = 8 - 10 + 5 = 3$

Simplify the denominator

First, solve $4 \times 15 \div 5$. Moving left to right: $4 \times 15 = 60$, and $60 \div 5 = 12$. For the second part, solve brackets first: $(8 \times 3) \div 6 = 24 \div 6 = 4$. Subtract these results: $12 - 4 = 8$.

$4 \times 15 \div 5 - (8 \times 3) \div 6 = 60 \div 5 - 24 \div 6 = 12 - 4 = 8$

Calculate the final ratio

Divide the simplified numerator by the simplified denominator. Note: Reviewing the steps, the calculation yields $3/8$. Since options are integers, verify the original expression.

$\frac{3}{8}$