A scale drawing represents a real object using a fixed ratio, so every length on paper is proportional to a real-world length. A scale of $1:500$ means $1\text{ cm}$ on paper represents $500\text{ cm}$ ($5\text{ m}$) in real life:

Worked example. A map has scale $1:25\,000$. A road measures $8.4\text{ cm}$ on the map. Find its true length in kilometres.

Worked example. A garden is to be drawn using a scale of $1\text{ cm}$ to $2\text{ m}$. The real garden is a rectangle $18\text{ m}$ by $11\text{ m}$. Find the dimensions of the scale drawing.

The scale drawing should measure $9\text{ cm}\times5.5\text{ cm}$ — always use a ruler for every straight edge in the finished drawing, since freehand lines lose accuracy marks even if the maths is correct.

A bearing gives a direction as an angle measured from north, clockwise, always written with three digits — $007^\circ$, $090^\circ$, $315^\circ$.

                North (000°)
                    │
   Bearing 315°     │     Bearing 045°
            \       │       /
West (270°) ──┼─────┼─────── East (090°)
            /       │       \
   Bearing 225°     │     Bearing 135°
                    │
                South (180°)

The compass directions north, east, south and west correspond to the fixed bearings $000^\circ$, $090^\circ$, $180^\circ$ and $270^\circ$. A phrase like "point $D$ is due east of point $C$" is simply another way of saying the bearing of $D$ from $C$ is $090^\circ$ — exam questions often switch between compass words and bearing numbers, so both descriptions must be treated as identical information.

The bearing of $A$ from $B$ is always $180^\circ$ different from the bearing of $B$ from $A$, since the north line drawn at $A$ is parallel to the north line drawn at $B$, and alternate angles between these parallel north lines link the two bearings:

Worked example. The bearing of a campsite $C$ from a car park $P$ is $118^\circ$. Find the bearing of $P$ from $C$.

Since $118^\circ < 180^\circ$, add $180^\circ$: $118^\circ + 180^\circ = 298^\circ$.

Worked example. A ship sails from port $A$ on a bearing of $250^\circ$ to reach point $B$. Find the bearing $A$ would appear on, if viewed from $B$.

Since $250^\circ \geq 180^\circ$, subtract $180^\circ$: $250^\circ - 180^\circ = 070^\circ$. The bearing of $A$ from $B$ is $070^\circ$.