Răspuns: [tex]\purple{\bf 5a + 7b + 2c = 177}[/tex]
Explicație pas cu pas:
[tex]\bf a + b = 23~~~~\bigg|\cdot 5~~ \implies \underline{5a + 5b = 115}[/tex]
[tex]\bf b + c = 31\bf ~~~\bigg|\cdot 2~~ \implies \underline{2b + 2c =62}[/tex]
[tex]\bf 5a + 7b + 2c =???[/tex]
[tex]\bf 5a + 5b = 115[/tex]
[tex]\bf \underline{2b + 2c = 62~~~~~~~~~} ( + )[/tex]
[tex]\bf 5a + 5b + 2b + 2c = 115 + 62[/tex]
[tex]\bf 5a + 7b + 2c = 115 + 62[/tex]
[tex]\red{\boxed{\bf 5a + 7b + 2c = 177}}[/tex]
[tex]==pav38==[/tex]