` \frac{9}{-15} = \frac{x+5}{10} `
` <=> -15(x + 5) = 10.9 `
` <=> -15x - 75 = 90 `
` <=> -15x = 150 `
` <=> x = -10 `
` \frac{3}{x+2} = \frac{5}{2x-1} `
` <=> 3(2x - 1) = 5(x + 2) `
` <=> 6x - 3 = 5x + 10 `
` <=> 6x - 5x = -10 + 3 `
` <=> x = -7 `
` \frac{2-x}{-3} = \frac{-27}{2-x} `
` <=> (2 - x)(2 - x) = -27.(-3) `
` <=> (2 - x)^{2} = 81 `
` <=> 2 - x = ±9 `
` TH1: `
` 2 - x = 9 `
` <=> x = -7 `
` TH2: `
` 2 - x = -9 `
` <=> x = 11 `
` \frac{-x}{9} = \frac{3}{x^{2}} `
` <=> -x.x^{2} = 3.9 `
` <=> -x^{3} = 27 `
` <=> -(x^{3}) = - (±3^{3}) `
` TH1: `
` -x = 3 `
` <=> x = -3 `
` TH2: `
` -x = -3 `
` <=> x = 3 ` `(ktm) `
` => x = -3 `
