(a) Expand and the similar terms will cancel out.

(B) Change the cube root into indices - fractionated form. Use the rule as shown to combine the two and expand. As you can see two terms cancel out and you are left with a^3. But remember the 1/3 power and times it in to give you the answer.
Hope it helps.

(c) Change to the indices form and expand everything using the previous rule in (b) you can multiply the numbers with the same powers and notice that they can cancelled out. For the first and last term, you can see that 9 = 3^2 and 4 = 2^2 respectively and thus you can multiply the 1/3 in with the power and continue the calculation from there.
Hope it helps!