What can i do with my daughter?

my daughter is 10 she is seriously struggling at school not just that she just dont understand anything she cant remeber anything she cannot think for herself the school have ordered testing that could tak e months me and my husband argue all the time she realies on her twin for everything recently they went camping had to share a tent because noone would share a tent with the problem daughter as she is very limited in understanding and can be very immature i have had enough of it all its a constant battle when im not battling her me and my husband are arguing our younger son has severe autisum and learning disabiltys also , whta should i do !