In order to calculate the discount, first let's find what percentage of the original amount was paid, by dividing the value charged by the original amount:
[tex]\frac{29.75}{85}=0.35=35\text{\%}[/tex]If the price charged is 35% of the original amount, the discount received is 100% minus this percentage:
[tex]\text{discount}=100\text{\%}-35\text{\%}=65\text{\%}[/tex]So the discount received is 65% of the original amount, that is, $55.25