Salutare!
a + b = 431
2 × a + 5 × b = 1696
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a + b = 431 ⇒ a = 431 - b
Inlocuim:
2 × ( 431 - b ) + 5 × b = 1696
862 - 2b + 5b = 1696
-2b + 5b = 1696 - 862
3b = 834
b = 834 : 3
b = 278
a = 431 - b ⇒ a = 431 - 278
a = 153
