Well, we know that the total amount is $420, so we can already set one side of the equation. =420. Also, it said that the $420 is (equal to) 7/6b (b for balance).
Now just put it together! 7/6b=420 is your answer.
Answer:
The empty set 
Step-by-step explanation:
Roster method is simply listing explicitly all the elements in the set, one by one (writing them between two curly brackets, and separating them through commas).
We want then to list explicitly all the elements in the following set:
The set of natural numbers x that satisfy x+2=1.
So, first we have to figure out which numbers are in that set. The set is made ONLY of those natural numbers x, that when you add 2 to them, you get 1. Clearly no natural number has that property (since the only number that would give us 1 when adding 2 to it, is the number -1, which is NOT a natural number). So there aren't any numbers at all in that set. So if we were to list them, we'd just list nothing inside the set:
(which is just the empty set)
Answer: 
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Work Shown:
Part 1

Part 2

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Explanations:
- There are quite a bit of steps. I decided to break things into two parts.
- The goal is to get x all by itself on its own side, which is why I subtracted (x-n)/n from both sides in part 1, step 2. I also subtracted p from both sides.
- Afterward, I gave each fraction the LCD mn. I multiplied top and bottom of the first fraction by n/n. I did a similar operation to the second fraction, but with m instead.
- From there, we distribute and simplify. The mn terms cancel on the left side numerator (second step of part 2).
- The n≠m is there to prevent the denominator (n-m) from being zero. We cannot divide by zero.
- If the formulas don't properly display, then you might have to refresh the page.
The answer is 5(x squared-3x)
It is distributive property