Solve in Under Ten Seconds

Practice solving five linear equations without writing anything. First: 2x + 7 = 19. Subtract 7 mentally: 2x = 12. Divide by 2: x = 6. Under three seconds with practice.

Second: 3(x - 2) = 15. Divide both sides by 3: x - 2 = 5. Then x = 7. Third: 5x - 4 = 2x + 11. Subtract 2x: 3x - 4 = 11. Add 4: 3x = 15. Divide: x = 5.

Fourth: 0.5x + 3 = 8. Subtract 3, then x = 10. Fifth: (x/3) + 2 = 6. Subtract 2, multiply by 3, land on x = 12. Run this drill each morning for a week, and solving becomes reflex.