• Escrevendo x e y em suas formas decimais:
[tex]\blacktriangleright x = \frac{1}{4} \cdot \frac{2}{5} : \frac{3}{20} = \frac{2}{20} : \frac{3}{20} = \frac{2}{20} \cdot \frac{20}{3} = \frac{40}{60}[/tex]
[tex]\blacktriangleright x = \frac{40}{60} \approx 0,67[/tex]
[tex]\blacktriangleright y = \frac{4}{3} \cdot \frac{5}{2} - \frac{5}{6} : \frac{5}{18} + 2 = \frac{20}{6} - \frac{5}{6} \cdot \frac{18}{5} + 2 = \frac{20}{6} - \frac{90}{30} + 2[/tex]
[tex]\blacktriangleright y = \frac{20}{6} - \frac{90}{30} + 2 = \frac{100 - 90 + 60}{30} = \frac{70}{30} \approx 2,33[/tex]
• Colocando o fator comum em evidência:
[tex]\blacktriangleright 7x - 21y = 7(x - 3y)[/tex]
[tex]\blacktriangleright 15a + 15b - 45c + 30 - d = 15 (a + b - 3c + 2) - d[/tex]
[tex]\blacktriangleright 5ab + 10ac - 20ad = 5(ab + 2ac - 4ad)[/tex]
[tex]\blacktriangleright 6mnp + 12mnr - 3mns = 3(2mnp + 4mnr - mns)[/tex]
