The user needs help solving 3 math problems: one on simultaneous equations, one on average speed, and one on map scale and area.

The solution is $\boxed{x=6, y=4}$.

2. In a shooting range, the target is placed 320 m away from the shooting point. If the bullet took $2\frac{1}{2}$ seconds to hit the target, what was the average speed of the bullet?

Distance ($d$) = 320 m
Time ($t$) = $2\frac{1}{2}$ s = 2.5 s

The average speed of the bullet was $\boxed{128 \text{ m/s}}$.

3. On a given map with scale of 1:600, a rectangular shape was measuring 6 cm by 2.5 cm. Find the actual area of the rectangular shape in square metres.

Actual length = Map length $\times$ Scale factor
Actual length = $6 \text{ cm} \times 600 = 3600 \text{ cm}$
Actual width = Map width $\times$ Scale factor
Actual width = $2.5 \text{ cm} \times 600 = 1500 \text{ cm}$

(1 m = 100 cm)
Actual length in meters = $\frac{3600 \text{ cm}}{100 \text{ cm/m}} = 36 \text{ m}$
Actual width in meters = $\frac{1500 \text{ cm}}{100 \text{ cm/m}} = 15 \text{ m}$

The actual area of the rectangular shape is $\boxed{540 \text{ m}^2}$.

4. Solve $\frac{2x - 6}{3} = \frac{x - 4}{4}$

The solution is $\boxed{x = \frac{12}{5} \text{ or } 2.4}$.

5. Factorise $4y - 144$

The GCF of 4 and 144 is 4.

The factorised expression is $\boxed{4(y - 36)}$.