Find the length of the side AB, if the perimeter of the figure is 45cm, and the side of the BC = 13cm

Find the length of the side AB, if the perimeter of the figure is 45cm, and the side of the BC = 13cm, CD = 10cm, DE = 7cm, EA = 5cm.

The perimeter is the sum of all the sides of the figure, therefore the perimeter minus the sum of all known sides will give the length of the uncovered sides. If there is only one such side, then its length will be obtained in this way:
Figure ABCDE, so the perimeter is defined as follows:
P = AB + BC + CD + DE + EA;
AB = P – (BC + CD + DE + EA) = 45 – (13 + 10 + 7 + 5) = 45 – 35 = 10 cm.