I added 6 to a certain number and then divide the result by 3. Find the number if my final answer is 5. (show working)

let the number be x

so (x+6)/3 =5

x+6=15

x=9

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3