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Stie cineva?Multumesc mult !

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Răspuns :

7.
a) x/y=4/9;   x=4; y=9

(3x+2y)/ (5x+y)=(3*4+2*9) / (5*4+9)=30/29

b) x/y=3/5; x=3; y=5

(4x+6y) / (x+y)= (4*3+6*5)/ (3+5)=42/8=21/4

c) x/4=y/7; 7x=4y; x/y=4/7; x=4; y=7

(9x-2y) / (x+3y)= (9*4-2*7)/ (4+3*7)=22/25