Answer:
9.2 ounce
Step-by-step explanation:
To do this, we divide $12 by 16 ounces, because there are 16 ounces in a pound:
12/16 = 0.75
Now, we need to find how many ounces can be bought for $4.80. To do this, we divide 6.90 by 0.75
=9.2 ounce
Part A is accomplished by first factoring out the b^2 to get

. Factor that completely using the quadratic formula to get

. Part B is done entirely with the quadratic formula (only cuz that's the easiest way to factor a second degree polynomial!) to get (x-9)(x-9) or (x-9) multiplicity 2. Part C is done by taking roots. Keep in mind that since this is a second degree polynomial you will have 2 solutions.

, therefore,

and

which is +11 and -11. And you're done! Factoring is very important...make sure you learn it and learn it well!!!
The 11/2 cup of black beans is extraneous info, you just need to know that it provides 15% of the potassium you need daily. With that info, you know that you need 85% more to fulfill your daily value. If we say x is the total amount of potassium needed, then we can set up the equation:
x * 0.85 = 2890
Then we can solve for x by dividing both sides by 0.85. The answer, then, is 2890/0.85 = 3400 mg.