Question: While practising for his upcoming math exams, Hayes realised that the area of a circle he had just solved was equal to the perimeter of a square he had solved in the previous problem. If the area of the circle was 100, what's the length of one side of the square?
Answer: Let's say the side of a square is s.To get the perimeter of a square, you add all the sides, which is s + s + s + s = 100. Therefore, 4s = 100. Therefore one side of the square is s = 100 / 4 = 25. The answer is 25.

Question: Five years ago, the sum of Sebastian's age and his sister's age was 3/4 of their father's age. How old is their father today if Sebastian is 40 years old and 10 years older than his sister?
Answer: If Sebastian is 40 years old and 10 years older than his sister, his sister is 40 - 10 = 30 years old. Five years ago, Sebastian was 40 - 5 = 35 years old. Similarly, Sebastian's sister's age was 30 - 5 = 25 years old. The sum of their ages five years ago was 25 + 35 = 60. Five years ago, the sum of Sebastian's age and his sister's age was 3 / 4 of their father's age, meaning their father's age was 60 / 3 / 4 = 80 years. The father's age is now 80 + 5 = 85. The answer is 85.

Question: Leila bought a living room set consisting of a sofa worth $1,250, 2 armchairs costing $425 each and a coffee table. The total amount of the invoice is $2,430. What is the price of the coffee table?
Answer: The price of 2 armchairs is $425 x 2 = $850. Mrs. Dubois will pay $850 for the 2 seats. Thus the Coffee table price is $2,430 – ($1,250 + $850) = $2,430 – $2,100 = $330. The answer is 330.

Question: A pen is longer than the rubber by 3 centimeters, and shorter than the pencil by 2 centimeters. Considering the pencil is 12 centimeters long, what is the total length of the rubber, the pen, and the pencil altogether?
Answer:
The pen is shorter than the pencil by 2 centimeters, so it's 12 - 2 = 10 centimeters long. That means the rubber is 10 - 3 = 7 centimeters long. So all accessories are 7 + 10 + 12 = 29 centimeters long altogether. The answer is 29.