The property of real numbers illustrated by the equation 16(3t+4v)=48t+ 64v.
Therefore, the answer is: Distributive property.
As you can see, you have the equation 16(3t+4v), and when you apply the Distributive property, you obtain:
16(3t+4v)
(16)(3t)+(16)(4v)
48t+64v
