Alvin, Marcus and Paul are schoolmates. Every Monday, they go to the same learning center from school at different times. Alvin leaves the school at 1 pm and reaches at 1 : 45pm. Marcus leaves the school at 2 : 05pm and reaches at 2 : 30pm. Paul leaves the school at 2 : 55pm and reaches at 3 : 25pm. Who takes the shortest time to reach the learning center among the three of them?
The frog, puppy and duckling participated in a swimming competition. The frog was not the first. The duckling saw the puppy and frog in front of it. Who won the competition?
Pi saved 2 dollars in the first month, 4 dollars in the second month, 6 dollars in the third, and so on. The amount of money he saved in the last month was 24 dollars. How much money did Pi save in total?
Danzel’s age is 2/9 of his mother’s age. Three years ago, his mother was 42 years old. In how many years’ time will Danzel’s age be 2/7 of his mother’s age?
The figure below shows a square ABCD, which is divided into 4 identical rectangles. The perimeter of each rectangle is 50cm. Find the area (in cm²) of the square ABCD.