Relation between ratio and percentage I would like to know easiest method to solve following:
Que: 
If $p$ is $128$% of $r$, $q$ is $96$% of $r$ and $r$ is $250$% of $s$, find the ratio of $p$:$q$:$s$.
My Approach:
Step 1: 
$p =\frac{128r}{100}$
$q = \frac{96r}{100}$
$r = \frac{250s}{100}$
So, $s = \frac{100r}{250}$
I do not know what to do further. 
I know the answer but don't know how to achieve Ans: $16$:$12$:$5$
Thank You!

Notice, $p, q, r$ all depend on $s$ as follows  $$r=\frac{250}{100}\times s=\frac{250s}{100}$$ 
$$q=\frac{96}{100}\times r=\frac{96}{100}\times \frac{250s}{100}$$ 
$$p=\frac{128}{100}\times r=\frac{128}{100}\times \frac{250s}{100}$$ 
hence, $$\color{red}{p:q:s}=\left(\frac{128}{100}\times \frac{250s}{100}\right):\left(\frac{96}{100}\times \frac{250s}{100}\right):(s)$$ $$=128:96:40$$
$$=\color{red}{16:12:5}$$
