Answer: 100
Step-by-step explanation:
18.47 is the answer when you add them together
(4ab^2-5ba-2ba^2+a^2+4b^3+a^3)(2b+a)/ a-4b^2
64 dollars is the tax, the total cost would be $864.
Use this for percentages.
https://percentagecalculator.net/
The given equation is: 
To find the line perpendicular to it, we interchange coefficients and switch the signs of one coefficient.
The equation to a line perpendicular to it is:
$ 2y-x=c$
where, $c$ is some constant we have determine using the condition given.
It passes through $(2,-1)$
Put the point in our equation:
$2(-1)-(2)=c$
$c=-2-2$
$c=-4$
The final equation is:
$\boxed{ 2y-x=-4}$