5/12÷(1/6+3/4)
=5/12÷11/12
=5/11
1/4×4/9+0.75×4/9
=(1/4+0.75)×4/9
=1×4/9
=4/9
79/100×101
=79/100×(100+1)
=79/100×100+79/100×1
=+79/100
=79又100分之79
(19/40+38)÷19
=19/40÷19+38÷19
=1/40+2
=2又40分之1
[3/8-(7/16-5/8)]÷9/10
=[3/8-7/16+5/8]÷9/10
=[1-7/16]÷9/10
=9/16×10/9
=5/8
=5/12÷11/12
=5/11