x = 14
a) a + b - 3 x = 56
a + b - 3 × 14 = 56
a + b - 42 = 56
a + b = 56 + 42
a + b = 98
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c) 7 × a + 7 × b + 7 × x = 700 l : 7 → impart relatia la 7
a + b + x = 100
a + b + 14 = 100
a + b = 100 - 14
a + b = 86
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e) 39 × a + 39 × b - 39 × x = 3 900 l : 39 → impart relatia la 39
a + b - x = 1 00
a + b - 14 = 100
a + b = 100 + 14
a + b = 114
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g ) x × a + x × b = 14
x × ( a + b ) = 14
14 × ( a + b ) = 14
a + b = 14 : 14
a + b = 1
