Let's make things easier by simplifying things.
y = 8 and x = 3 is more likely to be understood as a ratio. So for the rest of the answer, their relationship would be represented as y:x
Thus: y:x = 8:3
The problem would be finding y when x = 45
Let us proceed on using the previous equation and substitute x with 45 which would look like this:
y:45 = 8:3
Ratios can also be expressed as fractions which would make things more understandable and easy to solve. So the new form of our equation would be like this:
y/45 = 8/3
Then we proceed with a cross multiplication where the equation becomes like as what is shown below:
3y = 45 * 8
From there, you can solve it by multiplying 45 and 8 then dividing the product with 3 to get y
3y = 360
y = 120
Another way of looking at the problem, especially problems like these, is to take the whole question or statement as an equation. it would probably look like this:
y = 8 when x = 3 : y = ? when x = 45
This would make you understand what approach you can use to solve the given problem.
(a) Take the Laplace transform of both sides:
where the transform of 
comes from
![L[ty'(t)]=-(L[y'(t)])'=-(sY(s)-y(0))'=-Y(s)-sY'(s)](https://tex.z-dn.net/?f=L%5Bty%27%28t%29%5D%3D-%28L%5By%27%28t%29%5D%29%27%3D-%28sY%28s%29-y%280%29%29%27%3D-Y%28s%29-sY%27%28s%29)
This yields the linear ODE,
Divides both sides by 
:
Find the integrating factor:
Multiply both sides of the ODE by 
:
The left side condenses into the derivative of a product:
Integrate both sides and solve for 
:
(b) Taking the inverse transform of both sides gives
![y(t)=\dfrac{7t^2}2+C\,L^{-1}\left[\dfrac{e^{s^2}}{s^3}\right]](https://tex.z-dn.net/?f=y%28t%29%3D%5Cdfrac%7B7t%5E2%7D2%2BC%5C%2CL%5E%7B-1%7D%5Cleft%5B%5Cdfrac%7Be%5E%7Bs%5E2%7D%7D%7Bs%5E3%7D%5Cright%5D)
I don't know whether the remaining inverse transform can be resolved, but using the principle of superposition, we know that 
is one solution to the original ODE.
Substitute these into the ODE to see everything checks out:
12 ^3 and 11^3 haven't got the same base so the rules of exponents do not apply.
Bases have to be the same:- for example 12^3 * 12*3 = 12 ^(3+3) = 12^6
32/68 can be reduced to 8/17.
