Question

6e = ef + 3d?

Answer 1

In terms of e,
6e - ef = 3d
e(6 - f) = 3d
e = 3d/(6 - f)

In terms of d,
6e - ef = 3d
e(6 - f) = 3d
e(6 - f)/3 = d

In terms of f,
6e - 3d = ef
3(2e - d) = ef
3(2e -d)/e = f