First, distribute the -5 on the left side of the equation:

6x - 5(3x) + 5(0,5) = 3(7) - 3(3x)

Simplify the equation:

6x - 15x + 2,5 = 21 - 9x

Combine like terms:

-9x - 2,5 = -3x + 21

Add 9x to both sides:

-2,5 = 6x + 21

Subtract 21 from both sides:

-23,5 = 6x

Divide by 6:

x = -3,92