2/5:3/4,18/25:12/35,4/7:28
2/5:3/4=2/5X4/3=8/15 18/25:12/35=18/25X35/12=21/10=2.1 4/7:28=4/7x1/28=1/49
2/5 :3/4=8/15 18/25:12/35=21/10 4/7:28=1/49