Volume of Pyramid = (Base Area x Height)/3
Height = 15 mm (given)
Apothem = 7 mm (given)
Side = 12 mm (given)
Let's calculate the base area (or the pentagone area)
Base Area = (perimeter x apothem)/2. Perimeter = 5 sides x 12 = 60 mm
Base Area = (60 x 7)/2 = 210 mm²
Volume = (210 x 15)/3 = 1050 mm³