Respuesta :

1/5n -3/4+7/10n (collect the like terms 
1\5n+7\10n-3\4
1\5n+7\10n=(get the lcm of the denominators 5,10=10
(10\5=2*1=2)(10\10=1*7=7
2\10n+7\10n=9\10n
answer=9\10n-3\4