Răspuns:
Explicație pas cu pas:
x/y = 5/13
x = 5y/13
_________
a)
x + y = 5y/13 + y = 5y/13 + 13y/13 = 18y/13
(x + y)/y = (18y/13)/y = 18/13
b)
x/(x + y) = (5y/13) / 18y/13 = 5/18
c)
y - x = y - 5y/13 = 13y/13 - 5y/13 = 8y/13
(y - x)/x = (8y/13) / (5y/13) = 8/5
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(x - 3y)/(x + 3y) = 1/5
5(x - 3y) = x + 3y
5x - 15y = x + 3y
5x - x = 15y + 3y
4x = 18y
x = 18y/4 = 8y/2
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4x + y = 32y/2 + y = 16y + y = 17y
4x - y = 32y/2 - y = 16y - y = 15y
(4x + y)/(4x - y) = 17y/15y = 17/15