a/7 = b/3 --> a = 7b/3
a-b = 48
7b/3-b = 48
7b-3b = 144
4b = 144
b = 36.
a = 7b/3
a = 7.36/3
a = 7.12
a = 84.
Verificare : a-b = 84-36 = 48.
f) a/9 = b/7 --> a = 9b/7
2a+b = 75
2.9b/7+b = 75
18b/7+b = 75
18b+7b = 525
25b = 525
b = 21.
a = 9b/7
a= 9.21/7
a = 9.3
a = 27.
Verificare : 2a+b = 2.27+21 = 54+21 = 75.
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