Question

1;2;3;4 va rog mult de tot

Answer 1

$1) \frac{a}{b} = \frac{3}{8} \: | \times \frac{4}{3}$

$\frac{4a}{3b} = \frac{ 12 }{24}$

$\frac{4a}{3b} = \frac{ 1 }{2}$

$2) \frac{25x}{2y} = 6.25$

$\frac{25x}{2y} = \frac{625}{100}$

$\frac{25x}{2y} = \frac{125}{20}$

$\frac{25x}{2y} = \frac{25}{4}$

$25x \times 4 = 2y \times 25$

$100x = 50y \: | \div x$

$\frac{50y}{x} = 100$

$\frac{y}{x} = \frac{100}{50}$

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

$3) \frac{x}{y} = 0.5$

$\frac{x}{y} = \frac{5}{10} = \frac{1}{2}$

$y = 2x$

$\frac{2x + 3y}{5x - y} = \frac{2x + 3 \times 2x}{5x - 2x} = \frac{2x + 6x}{3x} = \frac{8x}{3x} = \frac{8}{3}$

$4) \frac{x}{y} = 0.(6)$

$\frac{x}{y} = \frac{6}{9} = \frac{2}{3}$

$3x = 2y$

$x = \frac{2y}{3}$

$\frac{x}{x + y} = \frac{ \frac{2y}{3} }{ \frac{2y}{3} + y} = \frac{ \frac{2y}{3} }{ \frac{2y}{3} + \frac{3y}{3} } = \frac{ \frac{2y}{3} }{ \frac{2y + 3y}{3} } = \frac{ \frac{2y}{3} }{ \frac{5y}{3} } = \frac{2y}{5y} = \frac{2}{5}$