Question

numerele a si b sint direct proportionale cu numerele 7 si 5 determinati numerele a si b daca a-b=12

Answer 1

a/7=b/5=k de unde rezulta a=7k si b=5k de unde rezulta a-b=12 rezulta 7k-5k=12 de unde rezulta 2k=12 de unde rezulta k=6 de unde rezulta a=42 si b=30

Answer 2

a-b=12
$\frac{a}{b}= \frac{7}{5}$
5a=7b
a=$\frac{7}{5}$b
$\frac{7}{5}$b-b=12
$\frac{7}{5}$b-$\frac{5}{5}$b=12
$\frac{7-5}{5} b=12$
[tex] \frac{2}{5} b=12 [/tex]
b=12 $\frac{5}{2}$
b=6*5
b=30
a=$\frac{7}{5}$*30
a=7*6
a=42