This math topic focuses on calculating the rate of simple interest given the principal, interest amount, and time period. The problems presented here involve computing the rate as a percentage based on varying scenarios in which the principal amount, the accumulated interest, and the duration of investment (in years) are specified. Participants are then required to select the correct rate percentage from multiple choices. This topic is an application of simple interest formula manipulation, enhancing skills in percentage calculation and algebraic manipulation related to financial mathematics.