Integrate the marginal cost function to find the cost function C(x).

The marginal cost is given by $\frac{dC}{dx} = 32 - 0.04x$.
To find $C(x)$, we integrate $\frac{dC}{dx}$ with respect to $x$:

$$C(x) = \int (32 - 0.04x)\,dx$$ $$C(x) = 32x - 0.04 \frac{x^2}{2} + K$$ $$C(x) = 32x - 0.02x^2 + K$$

where $K$ is the constant of integration.

It costs M50 to produce one shoe, which means $C(1) = 50$.
Substitute $x=1$ and $C(x)=50$ into the cost function:

$$50 = 32(1) - 0.02(1)^2 + K$$ $$50 = 32 - 0.02 + K$$ $$50 = 31.98 + K$$ $$K = 50 - 31.98$$ $$K = 18.02$$

Substitute the value of $K$ back into the cost function:

$$C(x) = 32x - 0.02x^2 + 18.02$$

The cost function $C(x)$ is:

$$C(x) = -0.02x^2 + 32x + 18.02$$