A's work rate = 1/12, B's work rate = 1/18. Together, they work at (1/12 + 1/18) = 5/36. Therefore, time = 36/5 = 7.2 days.

Let red balls be 3x and blue balls be 2x. Then, 3x + 2x = 30, 5x = 30, x = 6. Therefore, red balls = 3x = 3*6 = 18.

Let red = 4x and blue = 5x. Given 4x = 36, x = 9. Therefore, blue = 5x = 5*9 = 45.

Speed = 120 km / 2 hours = 60 km/h. Time = Distance / Speed = 180 km / 60 km/h = 3 hours.

Speed = 120 km / 2 hours = 60 km/h. Time = Distance / Speed = 300 km / 60 km/h = 5 hours.

Fuel consumption is 10 liters for 100 km, so for 250 km, it will need (250/100) * 10 = 25 liters.

5 liters for 100 km means 1 liter for 20 km. For 250 km, needed fuel = 250 / 20 = 12.5 liters.

Fuel consumption = 8 liters for 100 km, so for 250 km, needed fuel = (250/100) * 8 = 20 liters.

Rate = 300 gadgets / 4 hours = 75 gadgets/hour. In 10 hours, it produces 75 * 10 = 750 gadgets.

Rate = 300 gadgets / 4 hours = 75 gadgets/hour. In 10 hours, it produces 75 * 10 = 750 gadgets.

If 500 toys are produced in 10 hours, then in 25 hours, it will produce 500 * (25/10) = 1250 toys.

If 500 toys are produced in 10 hours, then in 25 hours, it will produce (500/10) * 25 = 1250 toys.

500 toys in 10 hours means 50 toys per hour. In 5 hours, it will produce 50 * 5 = 250 toys.

2 cups for 4 servings means 0.5 cups per serving. For 10 servings, 10 * 0.5 = 5 cups.

If 3 cups make 12 cookies, then 1 cup makes 4 cookies. For 30 cookies, needed cups = 30 / 4 = 7.5 cups, which rounds to 6 cups for practical purposes.

4 cups for 8 cookies means 1 cup for 2 cookies. For 20 cookies, 20/2 = 10 cups.

Let sugar = 2x and flour = 3x. Given 2x = 12, x = 6. Therefore, flour = 3x = 3*6 = 18.

Let sugar be 2x and flour be 3x. Given 3x = 12, x = 4. Therefore, sugar = 2x = 2*4 = 8.

Let sugar = 2x and flour = 3x. Given 2x = 12, x = 6. Therefore, flour = 3x = 3*6 = 18.

One pipe fills in 6 hours, so two pipes will fill in 6/2 = 3 hours.

One pipe fills in 6 hours, so two pipes will fill in 6/2 = 3 hours.

10 liters cover 200 m², so 1 liter covers 20 m². For 500 m², needed = 500 / 20 = 25 liters.

Work = 10 students * 15 days = 150 student-days. For 5 students, days = 150 student-days / 5 students = 30 days.

If 10 workers take 15 days, then 5 workers will take 15 * 10 / 5 = 30 days.

Cost per apple = $3 / 12 apples = $0.25. For 20 apples, cost = 20 * $0.25 = $5.00.

If 12 men take 30 days, then to complete in 15 days, we need 12 * (30/15) = 24 men.

12 men take 20 days, so to finish in 10 days, we need 12 * 20 / 10 = 24 men.

Cost per kg = $30 / 15 kg = $2. For 25 kg, cost = 25 * $2 = $50.

If 15 students take 20 days, then to complete in 10 days, we need 15 * (20/10) = 30 students.

15 students * 30 days = 450 student-days. For 10 students, days = 450 / 10 = 45 days.