4d + 12 = 4(d + 3) Basically, you just need to determine what 4d and 12 have in common. In this case, they both divide evenly by 4. Therefore 4 (d + 3) = 4d + 12 according to the distributive property.
If your talking about solar power its because its just not practical solar power doesnt put out nearly enough power for us to be able to run widespread as of yet new and more efficient solar power inc
