The phrase "are plain enough to" is correct and usable in written English.
It can be used to indicate that something is clear or obvious to a certain degree, often followed by a verb or an action.
Example: "The instructions are plain enough to understand without any further explanation."
Alternatives: "are clear enough to" or "are evident enough to".
This thesis is plain enough to require some padding.
The olive-green Chester coat, in a three-layer waterproof fabric, is plain enough to look elegant over a business suit.
"The theory behind it is plain enough: to reward success," said David A. Norcross, the former chairman of the rules committee of the Republican National Committee.
In "The Lord of the Rings," the errand of Frodo, though epic in execution, was plain enough: to destroy what would, in the wrong hands, cause irreversible harm.
Despite some of Mr. Helbers's knowing design details, especially in the mix of textures, the clothes were plain enough to make you seem invisible, one more dude in the lonely crowd.
Clark goes for whipped cream cheese and mayonnaise, which, in conjunction with the sausagemeat and grated Parmesan, makes his meatloaf almost too rich for my taste; this should be a dish that's plain enough to eat a hefty slice of.
Since the decomposition separates the convolution into P parts it is plain enough to solve the problem by multiple GPUs.
I'm not an insider on the subject of digital cinematography, but the difference at least in resolution should be plain enough to anyone who can count.
CARACAS, Venezuela — The ties between President Hugo Chávez and Cuba's Communist leaders are plain enough: Cuba has thousands of doctors here, not to mention a smaller number of advisers who help on a breadth of issues, like agricultural engineering and even training Olympic athletes.
Although the exact nature of their supposed transgression has yet to be made clear, the consequences are plain enough.
