Related Clues:

• Do sum basic math
• Put a couple of numbers together
• Do very simple math
• 'Figure it out yourself!'
• Subtract a negative number
• Append or attach to
• "You can figure it out"
• Sum; attach (to)
• 'Figure it out!' ... or how to arrive at this puzzle's solution, using the answers to italicized clues
• Use a + sign
• Put on extended promotion
• Total up some numbers
• Verb indicated by +
• Verb on a dipstick
• Opposite of take off