How can I solve question b). ?

It was not my intention to post that answer, as it does not solve the question, but hope it helps somehow.  

Step-by-step explanation:

You want to verify this identity.

The common denominator is

Solving the first and second numerator:

Now we have

Once

Also, consider the identity:

That last claim is true.

d. 8

step-by-step explanation:

the given radical expression is:

we can rewrite this as:

we express as square numbers to get;

the exponents will now cancel out to give.

the correct answer is d

so, converting firstly the mixed fractions to improper fractions and then "adding".