Răspuns :

5(7a+3b)=8(5a+b)
35a+15b=40a+8b
5a=7b
a/b=7/5
face produsul mezilor = produsul extremilor

5(7a+3b)=8(5a+b)
35a+15b=40a+8b
15b-8b=40a-35 a
7b=5a

[tex] \frac{a}{b} = \frac{7}{5} [/tex]