a, (-2/3)*2.x = (-2/3)*5

To solve for x, we can simplify the equation:

(-4/3)x = (-10/3)

Now, we can isolate x by dividing both sides of the equation by (-4/3):

x = (-10/3) / (-4/3)

x = (-10/3) * (-3/4)

x = 10/4

x = 5/2

Therefore, the solution for x in equation a is x = 5/2.

b, (-1/3)*3.x = 1/81

To solve for x, we can simplify the equation:

(-1)x = 1/81

Now, we can isolate x by dividing both sides of the equation by -1:

x = (1/81) / (-1)

x = (1/81) * (-1/1)

x = -1/81

Therefore, the solution for x in equation b is x = -1/81.

c, (x-1)*x + 2 = (x-1)*x + 6

To solve for x, we can simplify the equation:

x^2 - x + 2 = x^2 - x + 6

By subtracting x^2 and -x from both sides of the equation, we get:

2 = 6

This equation is not possible since 2 is not equal to 6. Therefore, there is no solution for x in equation c.