From Longman Dictionary of Contemporary Englishanswer/reply in the affirmativeanswer/reply in the affirmativeformal to say ‘yes’ → answer/reply in the negative at negative2(2) → affirmative
Examples from the Corpus
answer/reply in the affirmative• We can answer in the affirmative provided the weights are all positive.• No doubt Harry's family would also have replied in the affirmative, indicating that they really did not know what happiness was.• Are men more mechanical than women? 67% of all men responding to our poll answered in the affirmative.• That question was answered in the affirmative.• When asked if he recognized the defendant, the witness replied in the affirmative. 