Răspuns:
Explicație pas cu pas:
(4 + x)/(6 + x) = 9/11
11(4 + x) = 9(6 + x)
44 + 11x = 54 + 9x
11x - 9x = 54 - 44
2x = 10
x = 5
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(4 + x)/(6 + x) = 4/6
6(4 + x) = 4(6 + x)
24 + 6x = 24 + 4x
6x - 4x = 24 - 24
2x = 0
x = 0
_______________
(4 + x)/(6 + x) = 7/9
9(4 + x) = 7(6 + x)
36 + 9x = 42 + 7x
9x - 7x = 42 - 36
2x = 6
x = 6 :2 = 3
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succes la ultimul subpunct!
