Find the area of a rectangle if its area is 240m squared and one of the sides is 12m.

Let’s paraphrase the task: “Find the other side of a rectangle if its area is 240 m2, and one of the sides is 12 m.”

Given: Rectangle; its area S = 240 m2; side a = 12 m. Find side b.
Let’s use the formula for the area (S) of a rectangle through its sides (a and b): S = a * b.
If you know the area S of the rectangle and one of its sides (for example, side a), then the other side (b) can be found by the formula b = S / a.
We have b = S / a = (240 m2): (12 m) = (240: 12) m = 20 m.
Answer: 20 m.