Known quantity ÷ corresponding score (percentage) = quantity in "1"

Comparison Quantity ÷ Quantity in "1" = score (percentage)

Law of fractional addition and subtraction: Fractions with the same denominator are added and subtracted, only the numerator is added and subtracted, and the denominator remains the same. Fractions of different denominators are added and subtracted, first divided, then added and subtracted.

The multiplication of fractions is: use the product of molecules as numerator and the product of denominator as denominator.

The law of division of fractions: dividing by a number is equal to multiplying the reciprocal of this number.