Question 1: Working Hours and Wages

• Working hours increased by 20%
• Wages per hour increased by 15%
• Overall increase = (1.20 × 1.15 - 1) × 100% = 1.38 - 1 = 38%

Question 2: Alloy Percentage

• Metal A = 5 kg
• Metal B = 20 kg
• Total = 25 kg
• Percentage of A = (5/25) × 100% = 20%

Question 3: Profit Calculation

• Gain = 22.5% on cost price
• Sale = Rs. 392
• If cost is x, then x × 1.225 = 392
• x = 392/1.225 = 320
• Profit = 392 - 320 = Rs. 72

Question 4: Original Price Problem

• Initial condition: SP = 1.25 × CP
• New condition: (CP - 300) × 1.3 = SP - 300
• Step 1: Substitute SP = 1.25CP from first equation into second equation (CP - 300) × 1.3 = 1.25CP - 300
• Step 2: Expand left side 1.3CP - 390 = 1.25CP - 300