va rog ajutati maaaaa​

Explicație pas cu pas:

a)

c. a : b = c : d

b)

3 • 7 = 2 • (x + 1)

21 = 2 • x + 2

21 - 2 = 2 • x

19 = 2 • x

x = 19 : 2

x = 9,5

c. 9,5

[tex]\it a)\ \ \dfrac{a}{b}=\dfrac{c}{d}\ \iff\ a:b=c:d,\ deci,\ \hat\imath ncercuim\ litera\ C.\\ \\\\ \\ b)\ \ \dfrac{3}{x+1}=\dfrac{2}{7} \Rightarrow\dfrac{x+1}{3}=\dfrac{7}{2} \Rightarrow \dfrac{x+1}{3}=3,5 \Rightarrow x+1=10,5 \Rightarrow x=9,5[/tex]