<s>[INST] Working with functions 
Suppose $f(3-x)=2x^2-5x+4$ and $f(x)=ax^2+bx+c$. What is $a+b+c$? 

I don't know how to approach this. I thought of maybe doing $a(3-x)^2+b(3-x)+c=2x^2-5x+4$ and solving for $a+b+c$ but it got messy.
 [/INST] We know that $f(x)=ax^2+bx+c$  and so $f(1)=a+b+c$. Also, $f(3-x)=2x^2-5x+4$ and hence we get
$$a+b+c=f(1)=f(3−2)=2(2^2)−5(2)+4=2.$$
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