() kg is four fifths less than 40 kg, and one fourth more than 40 kg is () kg

() kg is four fifths less than 40 kg, and one fourth more than 40 kg is () kg

40×(1-4/5)=8
40×(1+1/4)=50.
In the case of one class, the unit 1 is known, multiplication is used. The unit 1 is unknown, division is used