Calculate Rectangle Area: Given Perimeter 30cm and Height 5cm

The perimeter of the rectangle equals the sum of all its sides, which means:

$P=AB+BC+CD+DA$

Since in a rectangle each pair of opposite sides are equal, we can say that:

$BC=AD=5$

This means that the two sides together equal 10, and now we'll subtract them from the perimeter and get:

$AB+DC=30-10=20$

This means sides AB and DC together equal 20, and since they are equal to each other, we'll divide 20 to find out how much each one equals:

$20:2=10$

Now we'll multiply side AB by side BC to find the area of the rectangle:

$10\times5=50$