B is the midpoint of AC. What is the length of AB? AB is 9x+7 and BC is -3x+20

If anyone has done the algebra 2 chaos theory portfolio would you be wiling to me? i kind of know what i'm doing i just don't know if i'm doing it right.

The liabilities of cullumber are $99,000. owner’s capital is $143,000; drawings are $96,000; revenues, $467,000; and expenses, $301,000. what is the amount of cullumber company’s total assists?

Having a hard time understanding this question (see attachment).