Answer:
a. you cannot multiply both sides by x because you do not know what x is.
Explanation:
Given:

Required
Select which of the option that applies
Considering (a):
A is incorrect:
Because: Multiplying both sides by x has nothing to do with whether the value of x is known or not
Considering (b):
B is incorrect:
Substitute 0 for x in the given expression


Both sides of the equation are undefined
However, you cannot assume x to be 0
Considering (c):
C is correct:
Start by multiplying both sides by x


Then, subtract 1 from both sides


Divide through by 3

Considering (d):
D is incorrect;
Because, the equation is linear