Equations and inequalities

What is the solution for x + 9 = 21

• 10
• 12
• 11
• 13

Solve for b
2b = -16

• 8
• 4
• -8
• 3

• x = 20
• x = 7
• x = 10
• x = 3

x - 8 = -5 

• 13
• -13
• 3
• -3

Solve:

• 96
• -96
• 4
• -4