To solve the equations, we will follow the steps below:

b) 2/3 - 4x = 1/2 - 2/5

First, let's find a common denominator for the fractions on the right side of the equation. The least common denominator (LCD) for 2 and 5 is 10.

Multiplying the numerator and denominator of 1/2 by 5, we get 5/10.

Multiplying the numerator and denominator of 2/5 by 2, we get 4/10.

Now, the equation becomes:

2/3 - 4x = 5/10 - 4/10

Simplifying the right side of the equation, we have:

2/3 - 4x = 1/10

To eliminate the fractions, we can multiply the entire equation by the LCD, which is 30:

30 * (2/3) - 30 * (4x) = 30 * (1/10)

This simplifies to:

20 - 120x = 3

Next, let's isolate the variable term by moving the constant term to the other side of the equation:

-120x = 3 - 20

-120x = -17

Finally, divide both sides of the equation by -120 to solve for x:

x = -17 / -120

Simplifying the fraction, we get:

x = 17/120

Therefore, the solution to the equation is x = 17/120.

c) 5/2x = -3/10 + 4/5

First, let's find a common denominator for the fractions on the right side of the equation. The least common denominator (LCD) for 10 and 5 is 10.

Multiplying the numerator and denominator of -3/10 by 1, we get -3/10.

Multiplying the numerator and denominator of 4/5 by 2, we get 8/10.

Now, the equation becomes:

5/2x = -3/10 + 8/10

Simplifying the right side of the equation, we have:

5/2x = 5/10

To eliminate the fractions, we can multiply the entire equation by the LCD, which is 10:

10 * (5/2x) = 10 * (5/10)

This simplifies to:

25/x = 5

Next, let's isolate the variable term by moving the constant term to the other side of the equation:

25/x = 5

Multiplying both sides of the equation by x, we get:

25 = 5x

Finally, divide both sides of the equation by 5 to solve for x:

x = 25/5

Simplifying the fraction, we get:

x = 5

Therefore, the solution to the equation is x = 5.