1/4 + 2/9 - 5/36= 9/36 + 8/36 - 5/36= 22/36= 11/18
3/4 + 4/5 + 1/20= 15/20 + 16/20 + 1/20= 32/20= 8/5
3/4 + 5/12 - 1/9= 27/36 + 15/36 - 4/36= 38/36= 19/18
4/15 + 2/5 + 7/10= 8/30 + 12/30 + 21/30= 41/30
1/4 + 2/9 - 5/36
= 9/36 + 8/36 - 5/36
= 22/36
= 11/18
3/4 + 4/5 + 1/20
= 15/20 + 16/20 + 1/20
= 32/20
= 8/5
3/4 + 5/12 - 1/9
= 27/36 + 15/36 - 4/36
= 38/36
= 19/18
4/15 + 2/5 + 7/10
= 8/30 + 12/30 + 21/30
= 41/30