Replace the blanks with + or - to make the statement correct

Hi my name is molly, and I have a question I can't answer and need your help. I am a student. This is the qustion:
Try to replace the blanks below with + or - to make the statement correct
1_2_3_4_5_6_7_8_9 = 1

I got the hint, but that didn't help me at all. thanks

Molly,

Start with something easier:

Try to replace the blanks below with + or - to make the statement correct
1_11_11_11_11 = 1

Claude