A 26 kg box rests on a level floor with µs = 0.48 and µk = 0.35…

Step 1. To start. $F = 0.48 \times 254.8\ \text{N} = 122.3\ \text{N}$.

Step 2. To keep it moving. $F = 0.35 \times 254.8\ \text{N} = 89.2\ \text{N}$.

Step 3. With $140\ \text{N}$. $a = \dfrac{140\ \text{N} - 89.2\ \text{N}}{26\ \text{kg}} = 1.95\ \text{m/s}^2$.