Contribution to sales ratio formula Steps:

• Calculate total sales revenue: 1000 units × $80/unit =$80,000.
• Sum variable costs: direct materials $10,000 + direct labour$6,000 + direct expenses $1,000 + variable overheads$7,500 = $24,500.
• Compute contribution: $80,000 -$24,500 = $55,500.
• Compute ratio: ($55,500 /$80,000) × 100% = 67%.

Why B is correct:

• It applies the standard formula for contribution to sales ratio, (sales revenue - variable costs) / sales revenue × 100%, yielding 67% based on given data.

Why the others are wrong:

• A is too low, possibly from assuming high fixed costs not present.
• C approximates variable costs to sales ratio (24,500 / 80,000 ≈ 31%, rounded up).
• D may result from averaging costs incorrectly without distinguishing variable from total.

Final answer: B