torque equilibrium question:?

Question

1. set the balancing holder at the 40 cm mark and placed the mass of 200g at the 20 cm mark. After that, we placed the unknown weight on another holder and adjusted its position on the ruler until we got the ruler horizontal balance. the ruler = 1m long and its weight is 150g. Find the unknown mass?

2. (Ruler = 1m long) set the balancing holder at the 25 cm mark of the ruler and placed the mass of 200g on the weight holder on the ruler in order to make the ruler balanced horizontally, and this position was 16cm. Find the mass of the ruler

Answer 1

Torques about the balance must be equal
Tccw = Tcw

I'm going to assume the 100 cm point is to the right. The mass of the ruler can be considered to be concentrated at 50 cm (10 cm from the pivot). Without the unknown, the meter stick would tilt ccw. So the unknown must be at a cm mark higher than 40, the pivot.
200 g*20 cm = 150 g*10 cm + m*d

m*d = 2500 g*cm

I think you left out some data.

2. Tccw = Tcw
200 g*9 cm = m*25 cm
m*25 cm = 1800 g*cm
m = 72 g