Foundation
USE WHEN
Percentages refer to different bases across statements.
BEST METHOD
Layered Base Method
TARGET
90–120 sec
MASTERY
not started
Percentages refer to different bases across statements.
Always convert each percentage statement into an equation with its own explicit base.
Use 100 as the lowest-level base, then build upward.
Start from the deepest base and build upward through multipliers.
Timed drill
Identify the base or invariant before you calculate.
Attempt first · Standard Example
Attempt first · CAT-Level Example
3-level practice ladder
Foundation
CAT Standard
Advanced / Hybrid
cat 2019 slot 2: a is 10% below b, b 25% above c, c 20% below d; changing-base chain.