5x-7y при x=14/20, y=15/21

Question

5x-7y при x=14/20, y=15/21

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Answer 1

5•14/20=70/20=3 1/2=3.5
7•15/21=105/21=5
3.5-5=-1.5

Answer 2

5x-7y при x=14/20, y=15/21

5*14 - 7*15 = 70- 105 = -35

5*20 - 7*21 = 100-147 = -47