What are the three ratios for 18:4
2 answers:
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Let's think about what happens when you find the price after tax. Let the price before tax be 
. The tax rate is 
, so the tax part of the total price is 
. Adding that onto the original price, we see that
So, we can just divide each side by
to get the original price, which rounded to two decimal places is 
.
So, we can just divide each side by
The unknown b is stuck in the exponent position.
We can can fix that by using logarithms.
Log is the inverse operation of the exponential.
We'll take log of each side.
Log of what base tho?
Well, the base of our exponential is e,
so we'll take log base e of each side.
We'll apply one of our log rules next:
This allows us to take the exponent out of the log,
Another thing to remember about logs:
When the base of the log matches the inside of the log,
then the whole thing is simply 1,
So our equation simplifies to this,
As a final step, divide both sides by 3,
k, hope that helps!