bjr

2x + 1 = -4

2x = -4 - 1

x = -5/2

x = -2,5

7 + 5x = 4

5x = 4 - 7

x = -3/5

4x - 3 = -7

4x = -7 + 3

x = -4/4 = - 1

-5 + 3x = 1

3x = 1 + 5

x = 6/3 = 2

-7x + 6 = 5

-7x = 5 - 6

x = 1/7

8 - 9x = -2

-9x = -2 -8

x = 10/9

ex 2

2/3 * 3/2x = 5 * 3/2

x = 15/2 = 7,5

5/7x * 7/5 = -8 * 7/5

x = -56/5

-3/4 * (-4/3) = -8 * (-4/3)

x = 32/3

-5/7x * (-7/5) = 3 * (-7/5)

x = -21/5