Question

aflati x din proportia

Answer 1

$a) \frac{3x}{28} = \frac{4.5}{4}$

$4 \times 3x = 28 \times 4.5$

$12x = 126$

$x = \frac{126}{12}$

$x = \frac{63}{6}$

$x = \frac{21}{2}$

$x = 10.5$

$b) \frac{2x}{2 \frac{1}{3} } = \frac{9}{ 5\frac{1}{4} }$

$\frac{2x}{ \frac{2 \times 3 + 1}{3} } = \frac{9}{ \frac{5 \times 4 + 1}{4} }$

$\frac{2x}{ \frac{7}{3} } = \frac{9}{ \frac{21}{4} }$

$2x \times \frac{21}{4} = 9 \times \frac{7}{3}$

$\frac{42x}{4} = \frac{63}{3}$

$\frac{42x}{4} = 21$

$42x = 4 \times 21$

$42x = 84$

$x = \frac{84}{42}$

$x = 2$

$c) \frac{0.3}{0.4} = \frac{1.35}{0.3x}$

$\frac{ \frac{3}{10} }{ \frac{4}{10} } = \frac{ \frac{135}{100} }{ \frac{3x}{10} }$

$\frac{3}{4} = \frac{ \frac{27}{20} }{ \frac{3x}{10} }$

$\frac{3}{4} = \frac{27}{20} \times \frac{10}{3x}$

$\frac{3}{4} = \frac{27}{2} \times \frac{1}{3x}$

$\frac{3}{4} = \frac{27}{6x}$

$3 \times 6x = 4 \times 27$

$18x = 108$

$x = \frac{108}{18}$

$x = \frac{54}{9}$

$x = 6$

$d) \frac{2x}{ \frac{2}{15} } = \frac{ \frac{1}{15} }{0.2}$

$\frac{2x}{ \frac{2}{15} } = \frac{ \frac{1}{15} }{ \frac{2}{10} }$

$2x \times \frac{15}{2} = \frac{1}{15} \times \frac{10}{2}$

$\frac{30x}{2} = \frac{1}{15} \times 5$

$\frac{30x}{2} = \frac{5}{15}$

$30x \times 15 = 2 \times 5$

$450x = 10$

$x = \frac{10}{450}$

$x = \frac{1}{45}$

$e) \frac{7x}{42} = \frac{15}{9}$

$7x \times 9 = 42 \times 15$

$63x = 630$

$x = \frac{630}{63}$

$x = 10$

$f) \frac{4x}{31} = \frac{44}{41}$

$4x \times 41 = 31 \times 44$

$164x = 1364$

$x = \frac{1364}{164}$

$x = \frac{682}{82}$

$x = \frac{341}{41}$

$g) \frac{ \frac{1}{6} }{2 \frac{1}{3} } = \frac{3.25x}{1.3}$

$\frac{ \frac{1}{6} }{ \frac{2 \times 3 + 1}{3} } = \frac{ \frac{325x}{100} }{ \frac{13}{10} }$

$\frac{ \frac{1}{6} }{ \frac{7}{3} } = \frac{ \frac{65x}{20} }{ \frac{13}{10} }$

$\frac{1}{6} \times \frac{3}{7} = \frac{ \frac{13x}{4} }{ \frac{13}{10} }$

$\frac{3}{42} = \frac{13x}{4} \times \frac{10}{13}$

$\frac{1}{14} = \frac{x}{2} \times 5$

$\frac{1}{14} = \frac{5x}{2}$

$5x \times 14 = 1 \times 2$

$70x = 2$

$x = \frac{2}{70}$

$x = \frac{1}{35}$