Marina spent 1/5 of her money on a book. If she had $80 left after she brought the book, how much money did she have originally?
2 answers:
Answer:
$100
Step-by-step explanation:
Step 1, setting up an equation:
If Marina spent of her money, <u>she has </u>
<u> of her money remaining</u>. We also are given that <u>she has $80 left</u>. We can set her initial total amount of money as <em>x</em> to solve this problem:
Step 2, solving for x:
We have set <em>x</em> as her original amount of money, so we have the answer!
Marina originally had dollars.
<em>I hope this helps! Let me know if you have any questions :)</em>
You might be interested in
For a quadratic of the form 
, we have the quadratic formula
,
where a is the coefficient (number before the variable) of the squared term, b is the coefficient of the linear term, and c is the constant term.
So, given
, we can get that 
, and 
. We substitute these numbers into the quadratic formula above.
This is our final answer.
If you've never seen the quadratic formula, you can derive it by completing the square for the general form of a quadratic. Note that the
symbol (read: plus or minus) represents the two possible distinct solutions, except for zero under the radical, which gives only one solution.
where a is the coefficient (number before the variable) of the squared term, b is the coefficient of the linear term, and c is the constant term.
So, given
This is our final answer.
If you've never seen the quadratic formula, you can derive it by completing the square for the general form of a quadratic. Note that the
Answer:
b =
Step-by-step explanation:
Given
a = ( multiply both sides by 3b - 2 )
a(3b - 2) = b + 1 ← distribute left side
3ab - 2a = b + 1 ( subtract b from both sides )
3ab - b - 2a = 1 ( add 2a to both sides )
3ab - b = 1 + 2a ← factor out b from each term on the left side
b(3a - 1) = 1 + 2a ( divide both sides by 3a - 1 )
b =