solve by elimination method

4/x + 5y = 7

3/x + 4y = 5

4/x +5y =7

4+ 5xy = 7x

similarly....

3+4xy = 5x 

now....

 (4+5xy = 7x ) 4

 (3+4xy = 5x ) 5

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16 + 20xy = 28x

15 + 20xy = 25x

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1 =3x

x= 1/3.....

and  y= (5-9)/4

y=-1.....