To find the tax rate when given the initial price of an object and the final tax value, you use the equation: $350 * X = $22.75 (where X is the sales tax rate). Then solve:
$22.75/$350 = .065
So the rate is 6.5%
Only problem is with the simplifying.
We all know that 5/5 = 1, it is natural to assume (x+a)/(x+a) is also 1, but in some cases where x+a=0, it is undefined. In this equation, where they simplify (x-2) and (x-6), you must say that x is not 2 nor 6 or, you just delete 0/0 which is undefined.
Therefore the only solution would be x=-1
(5x²+4x-80)(x²-5x-24)=5x²(x²-5x-24)+4x(x²-5x-24)-80(x²-5x-24)
{distributive property of multiplication}
=5x^4-25x³-120x²+4x³-20x²-96x-80x²+400x+1920
=5x^4-21x³-220x²+304x+1920
This is the answer.
