Practice.
Make it a game. Read to each other. She needs to read aloud. Count how many words per minute, set a realistic goal and work toward it. During reading, stop and ask comprehension questions to make she she understand what she is reading.
As for math, again, make it a game. At the grocery have her get 6 lemons, and how how many more make 10, etc... let her cook with you and see how you measure, etc. Practice.
Some schools have a summer program that helps children who are behind to keep up over the summer. If you can do this, do it. If not, make sure you set time daily to work with her. Even the simple things you do together with reading and math can make a world of difference. Keep it up over the summer so she does not fall behind.
Also, many schools offer FREE tutoring for about 45 minutes after school. If your teacher offers it do it.
Good luck