Problem 1: Leon uses 300g of cake mix. For every 100g of mix, he needs to add 30ml of water. So, for 300g of mix, he would need 300/100 = 3 times the amount of water. Therefore, he must add 3 * 30ml = 90ml of water.

Problem 2: Jacob has 3 boxes of bananas, each containing 60 bananas, so he has a total of 3 * 60 = 180 bananas. If he gives out 28 bananas, he will have 180 - 28 = 152 bananas left.

Problem 3: Arthur and Evan both go on three rides each, costing 75c per ride. So, Arthur spends 3 * 75c = $2.25, and Evan also spends the same, $2.25. Together, they spend $2.25 + $2.25 = $4.50 altogether.

Problem 4: If a pineapple costs 17c, then the number of pineapples that can be bought for $5 is given by $5 ÷ 17c. Therefore, the number of pineapples that can be bought is 500 ÷ 17 ≈ 29.41. Since you cannot buy a fraction of a pineapple, you can buy 29 pineapples for $5.

Problem 5: For 20 children's tickets at 50c each, the cost is 20 * $0.50 = $10. For 5 adult tickets at $1.20 each, the cost is 5 * $1.20 = $6. Therefore, the total cost for 20 children and 5 adults is $10 + $6 = $16.

Problem 6: Let's break down the number of cars:

• 6 red cars
• 16 white cars
• Since there were half as many blue cars as white, there are 16 / 2 = 8 blue cars.
• There were three times more black cars than blue, so there are 8 * 3 = 24 black cars.

Therefore, the number of black cars that went past is 24.