Question 158959
You have to include the function if x is less than $50. 
You use two functions that depend on the input value, 
1. {{{f(x)=x}}},{{{x<50}}}

{{{f(x)=x-10}}},{{{ x>=50}}}
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Remember you take the discount off of (subtracted from) the original price. 
2. {{{f(x)=x-(.20*x)}}}
You can simplify,
{{{f(x)=0.8*x}}}