The perimeter of the rectangle is 90 m. Find the width if the length is 24.

The opposite sides of a rectangle are equal, so their sum (perimeter) is calculated by the formula:
P = 2a + 2b.
Provided that P = 90 m, and the length is 24 m, we express the width of such a figure:
b = (P – 2a): 2. Substitute the values from the condition and write the expression:
b = (90 – 2 * 24): 2 = 42: 2 = 21 m.

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