The side of the square is 15 m, by what percentage will its area increase if the side is increased by 3 m?

To solve this problem, remember that the area of the square is equal to the square of the side. Let’s calculate the area of a square, knowing that the side is 15 meters.
S = 15 * 15 = 225 m ^ 2.
Let’s increase the side by 3 meters.
15 + 3 = 18 meters.
Let’s calculate the area of a square with a side of 18 meters.
S2 = 18 * 18 = 324 m ^ 2.
To find how many percent one number is from another, you need to find the quotient of these numbers, and then translate it into percentages (for this, multiply the resulting number by 100%).
324-225 = 99.
99/225 * 100 = 0.44 * 100 = 44%.
Answer: will increase by 44%.