Answer:

Step-by-step explanation:
Divide both sides by 

Simplify:
; 
Answer:
D
Step-by-step explanation:
Answer:
X= 30-4r/-6
Step-by-step explanation:
1. Move the 9 to the other side. (21+9=30)
2. subtract the 4r and move it to the other side (-6x=21-4r)
3. divide both sides by -6
Answer:
the answer would be 210:40
Step-by-step explanation: