1.2,5:1/4-1 1/5x20% 2.1,25-0,5x1/4 3.1/4+1,5:0,25

1.2,5:1/4-1 1/5x20%=25/10:1/4-11/5x20/100
=100/10x220/500
=22000/5000=4 2/5

2.1,25-0,5x1/4=125/100-5/10x1/4
=125/100-5/40
=1250/1000-125/1000
=1125/1000=1 125/1000
=1 125/1000= 1 5/40=1 1/8

3.1/4+1,5:0,25=1/4+15/10:25/100
=1/4+1500/250
=1/4+6=1/4+24/4=25/4=5 5/4