20道分数简算题（加减法）！！！！

1. 1/5+1/25+(1/6-3/5) 2. 7/36+5/6-2/9 3. 5/44-(7/30-2/11)+1/2 4. 1/2+1/3+1/4+1/5+1/6 5. 1+1/2+1/6+1/12+1/20+1/30+1/42 6. 2/35-3/5-6/7 7. 4/23+4&#