# Math Help - Rearrange the formula.

1. ## Rearrange the formula.

The formula is F= 35e^-0.7p

make p the subject.

Thanks in advance I am not sure where to start.

2. $F = 35e^{-0.7p}$

$\frac{F}{35} = e^{-0.7p}$

$\ln{\left(\frac{F}{35}\right)} = -0.7p$

$-\frac{10\ln{\left(\frac{F}{35}\right)}}{7}$.

3. You "undo" what has been done to p.

$35e^{-0.7p}= F$
The last thing done on the left is "multiply by 35" so the first thing you do to solve for p is divide both sides by 35:
$35e^{-0.7p}/35= e^{-0.7p}= \frac{F}{35}$

Now, we have an exponential function (e to a power). The reverse of that is the "natural logarithm". Take the logarithm of both sides:
$ln(e^{-0.7p})= -0.7p= ln(\frac{F}{35})$

Finally, p is multiplied by -0.7. Divide both sides by -0.7:
$-0.7p/(-0.7)= p= -\frac{ln(\frac{F}{35})}{0.7}$