a family got 20% off cupon for dinner they paid 45.70 how much was there discout?
If they paid 45.70 after the 20% discount the original cost must have been 45.70/0.8. The discount was therefore 0.2*45.70/0.8 = 45.70/4
$${\mathtt{discount}} = {\frac{{\mathtt{45.7}}}{{\mathtt{4}}}} \Rightarrow {\mathtt{discount}} = {\mathtt{11.425}}$$
discount = 11.43
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