I've always been able to manipulate equations found in school homework easily. But when tackling more challenging questions from puzzle books - where I might need three quarters of a page to manipulate the equation into the ideal form - I find myself easily making mistakes.
The obvious solution is more practice. But I can't find a suitable landfill of questions where the focus is on manipulating tediously long/complicated algebraic equations instead of practicing some kind of technique or problem.
Has anyone had the same problem as me and found a felicitous way to overcome it? (Other than the obvious advice to be more careful, which you have to sacrifice speed for unless you've already had lots of practice)
P.S. I'm not sure if this question belongs here; if it does not, I'll be glad to remove it.