Ответ:

вот решение

Пошаговое объяснение:

на листочке

1)

[tex] \frac{7 + x}{2} = \frac{5 + x}{4} \\ 4(7 + x) = 2(5 + x) \\ 28 + 4x = 10 + 2x \\ 4x - 2x = 10 - 28 \\ 2x = - 18 \\ x = - 18 \div 2 \\ x = - 9[/tex]

2)

[tex] \frac{2.5 + y}{0.5} = \frac{6 + 2y}{0.4} \\ 0.5(6 + 2y) = 0.4(2.5 + y) \\ 3 + y = 1 + 0.4y \\ y - 0.4y = 1 - 3 \\ 0.6y = - 2 \\ y = \frac{ - 2}{0.6} \\ y = - \frac{20}{6} \\ y = - \frac{10}{3} \\ y = - 3 \frac{1}{3} [/tex]

3)

[tex] \frac{4 - 6y}{3} = \frac{ \frac{1}{3}y - 2 }{ \frac{1}{2} } \\ 3( \frac{1}{3} y - 2) = \frac{1}{2} (4 - 6y) \\ y - 6 = 2 - 3y \\ y + 3y = 2 + 6 \\ 4y = 8 \\ y = 8 \div 4 \\ y = 2[/tex]

4)

[tex]\frac{1.5 - 4y}{ \frac{1}{4} } = \frac{ - 8 + 8y}{2} \\ \frac{1}{4} ( - 8 + 8y) = 2(1.5 - 4y) \\ - 2 + 2y = 3 - 8y \\ 2y + 8y = 3 + 2 \\ 10y = 5 \\ y = 5 \div 10 \\ y = 0.5[/tex]

5)

[tex] \frac{2.3x - 11.2}{7} = \frac{9.4 - 1.7x}{21} \: \: \: | \times 21 \\ 3(2.3x - 11.2) = 9.4 - 1.7x \\ 6.9x - 33.6 = 9.4 - 1.7x\\ 6.9x + 1.7x = 9.4 + 33.6 \\ 8.6x = 43 \\ x = 43 \div 8.6 \\ x = 5[/tex]

6)

[tex] \frac{4}{9} (1 \frac{1}{2} x - \frac{3}{8} ) = 1 \frac{5}{6} - 1 \frac{1}{3} x \\ \frac{4 \times 3}{9 \times 2} x - \frac{4 \times 3}{9 \times 8} = 1 \frac{5}{6} - 1 \frac{1}{3} x \\ \frac{2}{3} x + 1 \frac{1}{3} x= 1 \frac{5}{6} + \frac{1}{6} \\ 2x = 2 \\ x = 1[/tex]