The phrase "answer at hand" is correct and usable in written English.
It can be used when referring to a solution or response that is readily available or easily accessible.
Example: "With the answer at hand, we can proceed to the next step in our project."
Alternatives: "solution available" or "response ready".
But he was well-prepared and had a stock answer at hand: China values human rights but is a big, developing country and still needs to improve.
Put in a crude example, this would amount to saying that to ask for a system's energy is a well-defined question, while to ask for the square of the system's energy is not, even if, from our answer to the first question and trivial mathematics, we have a well-defined answer at hand.
With few immediate answers at hand, industry executives and analysts talk of elevated natural gas prices for years to come.
If these students (and their remorseful tutor) get cracking, they can all get As because they already have the answers at hand.
This is what defined my people: We did not believe, and what this meant, when I started on my path of metaphysical questioning, was that there were no ready answers at hand".
The oceans rise and the deserts creep in on us and various vital pillars wobble and fissure, but we will not starve for lack of supremely confident buttheads who'll have ready-made, surprisingly heated answers at hand when asked whether LeBron James is a True Winner.
Thirteen years later the answer is at hand, and it is unambiguously positive.
An answer is at hand, though it has been largely overlooked by members of Congress and the news media.
(Have a smart answer ready at hand).
The answer, amazingly, lies at hand.
Or how much of your hard-earned income goes to fund the Prison Service, schools or the NHS? Well the answer is close at hand and will soon be landing on your doormat.
