Problem : 3/4 + 1/2 = ?

5/4

Problem : 3/4 + 3/5 = ?

27/20

Problem : 7/10 - 2/15 = ?

17/30

Problem : 29/12 - 3/4 = ?

5/3

Problem : 9/70 + 11/105 = ?

49/210 or 7/30

Problem : 1/2 + 1/3 + 2/5 = ?

37/30

Problem : 7/2 - 1/6 - 9/10 = ?

73/30