1) 7/15- 5/12= 28-25/60 =3/60= 1/20 2) 3/14 + 1/2 =3 +7/14 = 10 / 14 = 5/7 3) 1 /20 * 5 / 7 = 1 * 5 / 20 * 7 = 1 / 28 4) 9 /56 - 1 / 28 = 9 - 2 / 56 =7 /56 = 1/ 8