urgent as I need to bake it tonight, three layer cake only want to make one layer I assume just divide the ingredients by three right ? any tips that

To both Smaug & Sara -
This is also true.
But/and in practice I find using either the white or the yolk (if I'm dividing a cake recipe) slightly changes the texture and taste of the finished product.
Also, it's messy and fussy to beat, say, 2 eggs and then take 2/3 of them for a recipe.
Your choice on division & technique.

It is kind of shaky ground, for sure. I'll sometimes dump part of an egg, but usually you can work out something fairly easy- the difference in a cake layer with, say, a whole egg yolk instead of 2/3 of one is well within acceptable limits. Also, when working in small quantities like this, things like the amount of material that sticks to a bowl or on a beater can become statistically significant. In general, I think uniformity is an overrated goal for a home cook; It may be a good idea to try to follow a recipe exactly the first time through, particularly if it's an author you have a lot of respect for, but after that I very seldom do anything the same way twice; it's usually not practical for a home cook to run a lot of experimental batches of something; usually the only time to experiment is with food you're counting on eating. Professionals need uniformity for marketing and financial reasons, but at home, variety is the spice of life.