（0.25+1/4×99）÷1/5
=(1/4+1/4×99)÷1/5
=(1+99)*1/4÷1/5
=100/4÷1/5
=25÷1/5
=5
3/4×97+3/4×3
=3/4*(97+3)
=3*100/4
=75
7/36÷11/12÷5/33
=7/36×12/11×33/5
=7/36×36/5
=7/5