Please help me with this problem. This is hard!! Thank you!!

Answer:
Part A. First option
Step-by-step explanation:
Part A:
Why Phebe use the exponent of 1/3 in Line 2?
Answer:
Phebe needed to rewrite the radical as an exponent in order to solve the equation and an exponent of 1/3 is equivalent to the cube root of a number:
[tex]\sqrt[3]{a} = a^{1/3}[/tex]
a= number