Angles on a Straight Line: Worked Example
22 October 2026
Understanding angles on a straight line is a key part of primary school maths and often comes up in 11+ exams. If your child can spot that angles on a straight line always add up to 180°, they are well on their way to solving these questions with confidence.
Worked example
On a straight line, one angle is 115°.
Angles on a straight line add up to 180°.
Subtract the known angle from 180°:
180° - 115° = 65°
The correct answer is 65°.
Angle chart
Straight line · 180°Key insight: Once your child knows this rule, they can quickly work out missing angles whenever one angle is given. This helps with many types of 11+ questions. Try more practice questions on maths.com uk to build their skills.
