Răspuns :
a) 5/x=20/7
5*7=20x
35=20x
x=35/20=7/4
b) x+1/3=10/9
(x+1)*9=3*10
9x+9=30
9x=30-9
9x=21
x=21/9=7/3
5*7=20x
35=20x
x=35/20=7/4
b) x+1/3=10/9
(x+1)*9=3*10
9x+9=30
9x=30-9
9x=21
x=21/9=7/3
[tex]a)\frac{5}{x}= \frac{20}{7} \\ \\ x= \frac{5*7}{20} \\ \\ x= \frac{35}{20} \\ \\ x= \frac{7}{4} \\ \\ b) \frac{x+1}{3} = \frac{10}{9} \\ \\ 9(x+1)=10*3 \\ \\ \\ 9x+9=30 \\ \\ 9x=30-9 \\ \\ 9x=21 \\ \\ x= \frac{7}{3} [/tex]