IBA / SAT Mathematics Study Notes
Linear Equations and Percentages
Linear equation: An equation in which the variable has power 1. Example: 3x + 5 = 20.
Fast method: Keep variable terms on one side and constants on the other, then divide by the
coefficient of the variable.
Example: 4x − 7 = 21 → 4x = 28 → x = 7.
Percentage
Core formula: Percentage = (part ÷ whole) × 100.
Useful shortcut: x% of N = (x/100) × N.
Example: 15% of 240 = 0.15 × 240 = 36.
Quick Practice
1 Solve: 7x + 9 = 44.
2 Find 18% of 350.
3 A price rises from 800 to 920. Find the percentage increase.
Prepared as a personal study resource.