It would take three and a half hours because for one person it takes alden 6 hrs while it takes anthony seven split it in half between them and a half because it takes his rother an extra hour to do it by himself .
<u>Given</u>:
The given expression is 
We need to determine how the expression can be simplified.
<u>Simplifying the expression:</u>
Let us determine how the expression can be simplified.
The expression is given by

Applying the exponent rule that
in the above expression, we get;

Adding the exponents, we get;

Again, applying the exponent rule
, we get;

Thus, the simplified expression is 
Hence, the expression is simplified by adding the exponents and keep the same base. Then find the reciprocal and change the sign of the exponent.
Therefore, Option D is the correct answer.
The correct answer is d, i got it right