Question

7x+8y=9, 3x + 5y = 7.
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Answer 1

Ответ:

x=-1; y=2

Объяснение:

7x+8y=9; 3x+5y=7

7x=9-8y; 3x+5y=7

x=9/7-8/7y; 3(9/7-8/7y)+5y=7

27/7-24/7y+5y=7

5y-3,3/7y=7-27/7

35/7y-24/7y=49/7-27/7

11/7y=22/7

y=22/7*7/11

y=2

x=9/7-8/7*2=9/7-16/7=-7/7=-1