M1 friction on inclined plane

Clearly you are resolving up the plane. Also clearly, left alone the package slides down the plane. Friction opposes motion. So friction acts up the plane. So it is positive are you are resolving upwards.

Sure. Do you see why that same chain of reasoning means that friction acts down the plane in (b)?

Slice the triangle down halfway from the vertex. This gives two equal right-angled triangles, each with base 3, hypotenuse 5 and so height 4. Hence has area $\frac{1}{2} \times 3 \times 4 \times 2$ (since there are two such triangles).

Edit: In case this still isn't clear, the reason why each triangle has a base of $3$ is because it's slices the side of the square in half, which has length $6$.

could you say what the answer is. I have M1 tomorrow and I'm quite stressed.