Simplify Expressions by Combining Like Terms

Which of these are like terms in the following expression:
3x + 7 - 9x + 24y + 2x²

• 7, 24y
• 3x, 9x
• 3x, -9x
• 3x, -9x, 2x²

Simplify by combining like terms:
5a + 2b - 3a + 4

• 8a + 2b + 4
• 2a + 2b + 4
• 8ab
• 4ab + 4

Simplify by combining like terms:
4x² - 3x + 11 -2x

• 4x² - 5x + 11
• 11x + 11
• 16x² - 5x + 11
• 10x²

Simplify by combining like terms:
5a + 2b - 3a + 4

• 8a + 2b + 4
• 2a + 2b + 4
• 8ab
• 4ab + 4

-r - 10r

• 11r
• -11r
• 9r
• -11

Simplify the expression: 2x + 1 + 7x 

• 10x
• 10
• 9x + 1
• 9 + 1x

n -10 +9n -3=

• -3
• 9n-3
• n
• 10n -13

Simplify the expression: 7v + 2 + 12 + 2v

• 23
• 23v
• 9 + 14v
• 9v + 14

Combine like terms
3x + 2x + 3y - 7y

• 5x + 10y
• 5x + 4y
• 5x - 4y
• 5x -10y

n -10 +9n -3=

• -3
• 9n-3
• n
• 10n -13