Question

daca a/3=b/4=c/7 si a+b+c=70 aflati numerele a,b, c,

Answer 1

a+b+c=70

a/3=b/4=c/7

a=3k

b=4k

c=7k

3k+4k+7k=70

14k=70

k=70:14

k=5

a=3×5

a=15

b=4×5

b=20

c=7×5

c=35

Answer 2

$\it \dfrac{a}{3}= \dfrac{b}{4}= \dfrac{c}{7} = \dfrac{a+b+c}{3+4+7}= \dfrac{70}{14}=5\Rightarrow\begin{cases}\it a=3\cdot5=15\\ \\ \it b=4\cdot5=20\\ \\ \it c=7\cdot5=35\end{cases}$