Hello.
Firstly, let's isolate x on the equation:

Now, we can replace 'x' for 'y' and vice-versa:

Hope I helped.
Getting the percentage increase, we can form the formula or equation.
Percentage increase = ($1.00 - $0.40) / $0.40 * 100
<span>Percentage increase = ($0.60) / $0.40 * 100
</span><span>Percentage increase = 1.5 * 100
</span><span>Percentage increase = 150%
</span>
So there is a 150% increase from the original price.
I am pretty sure it is customary
D(e^(In(x))^2)/dx = 2 In(x) * 1/x * e^(ln(x))^2 = (2e^(ln(x))^2 * In(x)) / x