Line 7 on my 2018 tax return is blank what am i supposed to put for my adjusted gross income?

For the 2018 Tax Return:

Complete Schedule 1.

Add the values from the 1040 Lines 1-5. 

Then add any amount from Schedule 1, Line 22.  This will give you the value for Line 6.  

Then Line 7 instructions are "If you have no adjustments to income, enter the amount from Line 6; otherwise, subtract Schedule 1, Line 36 from Line 6." to give the value for Line 7.

Hope this helps!

If your 2018 AGI was zero, use 0 when go to E-file.   How do I find last year’s AGI?