Answer:
b = 3, which is an extraneous solution because if we replace b = 3 in the equation, we must be 5/0 and 30/0, and there is division by 0.
Step-by-step explanation:

The minus common multiply must be (b-3)*(b+3) = b² - 9

7b - 21 + 5b + 15 = 10b
2b = 6
b = 3
Which is an extraneous solution because if we replace b = 3 in the equation, we must be 5/0 and 30/0, and there is division by 0. So this solution is invalid.
Answer:
x=2
Step-by-step explanation:
Answer: x = 10
Step-by-step explanation: 7x10 = 70