3% represents a monthly interest of 0.3% and a loan of 20,000 yuan. 3% monthly interest = 20000×0.3%× 1 = 60 yuan, multiplied by 6 months, that is, you need to repay the interest 360 yuan.

People generally use Li to express loan interest, Li is the unit of measurement, meaning a few thousandths. If it is used to express interest, it is usually monthly interest, because daily interest is calculated in ten thousand units and annual interest is calculated in percentage.