What is 3(8+6n)=6n-12

3(8 + 6n) = 6n - 12 equals n = -3.

First, expand. Your problem should look like: 24 + 18n = 6n - 12.
Second, subtract 6n from both sides. Your problem should look like: 24 + 18n - 6n = -12.
Third, simplify 24 + 18n - 6n to 24 + 12n. Your problem should look like: 24 + 12n = -12.
Fourth, subtract 24 from both sides. Your problem should look like: 12n = -12 - 24.
Fifth, simplify -12 - 24 to -36. Your problem should look like: 12n = -36.
Sixth, divide both sides by 12. Your problem should look like: n = - .
Seventh, simplify  to 3. Your problem should look like: n = -3, which is your answer. 

Volume of emerald = 137.04cm³

Step-by-step explanation:

Given that:

Mass of emerald = 378.24grams

Density of emerald = 2.76grams/cm³

Volume = ?

The equation for this relationship is ρ = m / V in which ρ is density, m is mass (kg or g) and V is volume (cm³ or m³) making the density unit kg/m³ or g/cm³.

Therefore

Density = mass/volume

Volume = Mass/density

i.e

Volume of emerald = Mass of emerald / Density of emerald

Volume of emerald = 378.24grams / 2.76grams/cm³

Volume of emerald = 137.043cm³ ~137.04cm³

Volume of emerald =137.04cm³