A uniform metre scale has a mass M that we do not know…

Step 1. The first balance. The knife edge is at $29.0$ cm. The $200.0$ g mass is $29.0 - 5.0 = 24.0$ cm to the left. The centre of the scale is $50.0 - 29.0 = 21.0$ cm to the right. Moments: $200.0\ \text{g} \times 24.0\ \text{cm}$ $= M \times 21.0\ \text{cm}$. We want $M$, so $M = \dfrac{200.0 \times 24.0}{21.0}\ \text{g} = 229$ g.

Step 2. The second balance. The knife edge is at $62.0$ cm. The body is $95.0 - 62.0 = 33.0$ cm to the right. The centre of the scale is $62.0 - 50.0 = 12.0$ cm to the left. Moments: $m \times 33.0\ \text{cm}$ $= 228.6\ \text{g} \times 12.0\ \text{cm}$. So $m = \dfrac{228.6 \times 12.0}{33.0}\ \text{g} = 83.1$ g.