60-second card
Simplifying ratios
A ratio compares quantities. Simplify it by dividing every part by the same number.
- 24 : 36 → divide by 12 → 2 : 3.
- To join a : b and b : c, make the b parts equal first.
- Proportion: a : b = c : d means a × d = b × c.
Example: a : b = 2 : 3 and b : c = 4 : 5. Make b = 12: a : b = 8 : 12, b : c = 12 : 15. So a : c = 8 : 15.
Remember: Divide all parts by their highest common factor.
Common mistake: Adding the same number to both parts. That changes the ratio.