Method 1: Calculate decrease then subtract. 8% of 5000 = 0.08 × 5000 = 400 New population = 5000 - 400 = 4600 Method 2: Use multiplier. Decrease of 8% means 100% - 8% = 92% remains New population = 0.92 × 5000 = 4600 Therefore, the new population is 4600.Step 1: Calculate the profit. Profit = Selling price - Buying price Profit = $230,000 - $200,000 = $30,000 Step 2: Calculate the percentage profit. Percentage profit = (Profit / Original price) × 100 Percentage profit = (30,000 / 200,000) × 100 Percentage profit = 0.15 × 100 = 15% Therefore, the percentage profit is 15%.Simple Interest formula: I = PRT Where P = Principal, R = Rate (as decimal), T = Time P = $2000 R = 5% = 0.05 T = 3 years I = 2000 × 0.05 × 3 I = 2000 × 0.15 I = $300 Therefore, the simple interest is $300.Step 1: Understand what $64 represents. After 20% discount, the customer pays 80% of the original price. 80% of original = $64 Step 2: Find the original price. Let original price = x 0.80 × x = 64 x = 64 ÷ 0.80 x = $80 Check: 20% of $80 = $16, so $80 - $16 = $64 ✓ Therefore, the original price was $80.Depreciation means decrease in value. Step 1: Find the multiplier. 100% - 12% = 88% = 0.88 Step 2: Calculate the new value. New value = Original value × Multiplier New value = $15,000 × 0.88 New value = $13,200 Therefore, the car is worth $13,200 at the end of the year.Step 1: Understand what $690 represents. After 15% increase, the new price is 115% of the original. 115% of original = $690 Step 2: Find the original price. Let original price = x 1.15 × x = 690 x = 690 ÷ 1.15 x = $600 Check: 15% of $600 = $90, so $600 + $90 = $690 ✓ Therefore, the original price was $600.Simple Interest formula: I = PRT P = $3500 R = 4% = 0.04 T = 18 months = 18/12 = 1.5 years I = 3500 × 0.04 × 1.5 I = 3500 × 0.06 I = $210 Therefore, the interest earned over 18 months is $210.
