Which expression has the same value as 79.2-94.6

In triangle abc segment de is parallel to the side ac . (the endpoints of segment de lie on the sides ab and bc respectively). find de, if ac=20cm, ab=17cm, and bd=11.9cm;

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Olga bought a new skirt that cost $20. sales tax is 5%. how much did olga pay, including sales tax? 7.