X+3=18

Solution:

• x + 3 = 18
• Subtract 3 from both sides: x = 18 - 3 = 15
• Check: 15 + 3 = 18 ✓

General tip: For equations of the form x + a = b, the solution is x = b − a. If you have something like ax + b = c, you’d first isolate x by appropriate inverse operations. Want a couple more practice problems?