Answer:
See Below.
Step-by-step explanation:
We want to verify:

We will utilize the following identities:

And:

So, by substitution, we acquire:

Distribute:

The first and third term will cancel:

Combine like terms:

A) 3x+4=21
3x=21-4
3x=17
x=17÷3
x= 5.7
Answer:
29
Step-by-step explanation: