(0.003999 X 10^8) + (6.00111 X 10^8)

6.005109 x 10⁸

Explanation:

Given expression:

      (0.003999 x 10⁸) + (6.00111 x 10⁸)

Now, to solve for this sum,

   take the coefficient and sum:

     =  (0.003999 + 6.00111) x 10⁸

     = 6.005109 x 10⁸

In this kind of problem, just make sure the exponent parts are the same then add the coefficient together.

3 hours because it is a decent distance.

i do not get it   at all