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Se stie ca 7a+3b=29si a+b=7.Aflati numerele a si b

PLS AJUTOR


Răspuns :

7a+3b=29
a+b=7 ⇒ a=7-b
7(7-b)+3b=29
49-7b+3b=29
4b=49-29=20
b=20:4
b=5
a=7-5
a=2
V: 7x2+3x5=14+15=29