A 5.0 kg block lies on a smooth slope at 28°…

Step 1. The two pulls. Hanging: $3.5\ \text{kg} \times 9.8\ \text{m/s}^2 = 34.3\ \text{N}$. Down the slope: $5.0\ \text{kg} \times 9.8\ \text{m/s}^2 \times \sin 28^\circ = 23.0\ \text{N}$. The hanging block wins and falls.

Step 2. Acceleration. $a = \dfrac{34.3\ \text{N} - 23.0\ \text{N}}{5.0\ \text{kg} + 3.5\ \text{kg}} = \dfrac{11.3\ \text{N}}{8.5\ \text{kg}} = 1.33\ \text{m/s}^2$.

Step 3. Tension. For the hanging block, $mg - T = ma$: $T = 3.5\ \text{kg} \times (9.8\ \text{m/s}^2 - 1.33\ \text{m/s}^2) = 29.6\ \text{N}$.