Answer:
Below 
Explanation:
a) Density = mass/ volume 
 you are given mass ( 6725kg) and volume (2.5 m^3) and you want 
 kg / m^3 this would be 6725 kg / 2.5 m^3 = 2690 kg/m^3 
b) given density = 2690 kg/m^3 multiply by m^3 to get kg 
 2690 kg / m^3 * 1.3 m^3 = 3497 kg