The phrase "able to vary" is correct and usable in written English.
It can be used when discussing the capacity or capability to change or adapt something.
Example: "The settings on this device are able to vary according to user preferences."
Alternatives: "capable of changing" or "able to adjust".
By varying the carbon source temperature, we are able to vary the dominant carbon source from just chlorobenzene to PMMA.
Americans, they say, should be able to vary their identity.
"So all schools will be able to set their own dates and be able to vary them.
For example, in the demonstration Epic was able to vary the brightness of a scene when the sun passed behind a cloud.
It will also give all MPPI customers clarity about when and why firms will be able to vary these in future".
A monopolistic exporter, such as De Beers in the diamond industry, may be able to vary prices in different countries without risking arbitrage.
Following G-Day, as it is known in the industry, insurance companies are no longer able to vary premiums according to a policyholder's sex, the result of a 2011 European court of justice ruling.
Some contracts provide for employers to be able to vary the type of work that you are given, whereas others are more specific in the nature of your role and responsibilities.
Skilled chefs, though, are able to vary the taste of a dish by choosing precisely what quantities of individual ingredients go into the pot, and that, more or less, is what epigenetic mechanisms do.
Even on the second, more controversial question of whether the parliament should be able to vary the basic rate of income tax by up to 3p in the pound, a clear majority says "yes".
Composite orientation is able to vary joints mechanical properties significantly.
