Question

1/2+ 2/5, 1/2-2/5,1/4+1/6,9/10-5/6

Answer 1

9/10,1/10,5/12,2/30=1/15

Answer 2

1/2+2/5=3+4/10=9/10
1/2-2/5=1/10
1/4+1/6=3+2/12=5/12
9/10-5/6=27-23/30=1/15