'SalesTaxPct' was not declared in this scope
<p>I am new to C++.  I am struggling with the pass by value thing, and no one can explain what I am doing wrong to me in a way I can understand. I know this is my fault, but Ii am asking for help with my code. HELP PLEASE!</p>

<pre><code>#include &lt;iostream&gt;
using namespace std;

double getValues();
double getSalesTax(double SalesTaxPct);
double gettotal_price(double base, double opt);
void PrintFinal(double base,double opt,double SalesTaxPct);

// function to control all other functions
int main()
{
    getValues();
    getSalesTax(SalesTaxPct);
    PrintFinal(base,pt,SalesTaxPct);
}

// function to calculate sales tax percent into decimal 
double getSalesTax( double SalesTaxPct )    

{
    double SalesTax;

    SalesTax = SalesTaxPct / 100;

    return SalesTax;
}



// function to find total
double gettotal_price(double base, double opt, double SalesTax)

{

    return = (base + opt) * (1 + SalesTax);


}


// function to show user all values input and also total
void PrintFinal(double base, double opt, double SalesTaxPct)

{
    cout &lt;&lt; "Base vehicle price: $" &lt;&lt; base &lt;&lt; endl;

    cout &lt;&lt; "Options Price: $" &lt;&lt; opt &lt;&lt; endl;

    cout &lt;&lt; "Sales tax pct: " &lt;&lt; SalesTaxPct &lt;&lt; "%" &lt;&lt; endl;

    cout &lt;&lt; "Total vehicle price: $" &lt;&lt; gettotal_price(double base, double opt, double SalesTax) &lt;&lt; endl;

}


// function to get input values
void getValues()
{
    double base, double opt, double SalesTaxPct;

    cout &lt;&lt; "Enter a base vehicle price: " &lt;&lt; endl;
    cin &gt;&gt; base;

    cout &lt;&lt; "Enter options price: " &lt;&lt; endl;
    cin &gt;&gt; opt;

    cout &lt;&lt; "Enter a sales tax percent: " &lt;&lt; endl;
    cin &gt;&gt; SalesTaxPct;


}
</code></pre>
