The area of the romboide is: $$$A=a \cdot h$$$
Its perimeter is: $$$P=2 \cdot (a+b)$$$
Calculate the area of a rhomboid with $$a=5 \ cm$$ and of height $$3 \ cm$$
$$$A=3 \ cm \cdot 5 \ cm=15 \ cm^2$$$
And so, the area of the romboide is: $$15 \ cm^2$$.