To solve this exercise, we can follow these steps.
Step 1: The original formula to find the perimeter of a rectangle is P = 2L + 2W.
Step 2: We want to isolate the variable L, which stands for the length of the rectangle.
Step 3: The first action we'll take is to remove the term 2W on the right side of the equation. To maintain the equation's balance, we need to perform any operations we apply on one side to the other side as well.
Step 4: So we subtract 2W from both sides, this gives us P - 2W = 2L.
Step 5: We're still solving for L, so we'll next need to eliminate the 2 adjacent to the L.
Step 6: Since 2L means '2 times the length', to reverse this operation, we'll divide both sides of the equation by 2.
Step 7: Dividing both sides by 2 results in (P - 2W) / 2 = L.
Step 8: And that's our final answer. We've managed to re-arrange the formula to solve for L: L = (P - 2W) / 2.
Now, using this formula, we can calculate the length if we know the perimeter and the width of the rectangle.