Width of the first brick (half brick wall), w_{1} = (13.6 ± 0.1) cm

Width of the second brick (full brick wall), w_{2} = (23.6 ± 0.1) cm

For finding the __uncertainty__ in the difference, we add the uncertainties in the two measurements in the result (sum).

Difference in the widths of walls = (23.6 ± 0.1) cm – (13.6 ± 0.1) cm = (23.6 – 13.6)cm ± (0.1 + 0.1)cm = **10 cm ± 0.2 cm**. (Answer)