a)
[tex] \frac{7}{x} = \frac{1}{3} \\ 7 \times 3 = 1 \times x \\ 21 = x[/tex]
b)
[tex] \frac{3x}{5} = \frac{2}{2.5} \\ 3x \times 2.5 = 2 \times 5 \\ 7.5x = 10 \\ x = \frac{10}{7.5} = 1 \frac{2.5}{7.5} = 1 \frac{1}{3} [/tex]
c)
[tex] \frac{4}{9} = \frac{2x}{27} \\ 4 \times 27 = 9 \times 2x \\ 108 = 18x \\ x = 6[/tex]
d)
[tex] \frac{x + 3}{9} = \frac{2}{5} \\ (x + 3) \times 5 = 2 \times 9 \\ 5x + 15 = 18 \\ 5x = 18 -15 \\ 5x = 3 \\ x = \frac{3}{5} [/tex]
Myślę że pomogłem ;)
