The rectangle is 5 cm wide and less than 26 cm perimeter. Estimate the length.

Given:
rectangle
width = 5 cm
perimeter = 26 cm
Find the length
Decision:
Since, according to the formula, perimeter = 2 * (width + length), then we substitute the known values into the formula.
Let x be the length of the rectangle, then
26 = 2 * (5 + x)
5 + x = 26/2
5 + x = 13
We transfer the known values to one side, and the unknown ones to the other side. When transferring meanings, their signs change and the opposite sign. That is, we get
x = 13 – 5
x = 8 cm
That is, the length of the rectangle is 8 cm
Answer: length = 8cm