3x+5=20

Solution:

• Start with 3x + 5 = 20
• Subtract 5: 3x = 15
• Divide by 3: x = 5

Check: 3(5) + 5 = 15 + 5 = 20, which is correct.

General note: For ax + b = c (a ≠ 0), x = (c - b)/a.