回报(huí bào) - to repay, to reciprocate; return, reward in Mandarin

回报 (huí bào) is to give something back to someone who gave first. As a verb it takes the person or the kindness as its object: 回报你的帮助, 回报父母. As a noun, with no change of form, it is the return or reward that comes back to you.

It is common in two very different settings. Emotionally, 不求回报 (asking nothing in return) is a set phrase for selfless help. Commercially, 投资回报 is return on investment and 回报率 is the rate of return, so the word is at home in a business report as well as a thank-you note.

The trap is 回答. Both start with 回, but 回答 is to answer a question and 回报 is to pay back a debt of kindness or money. Getting them the wrong way round turns thank you for your help into an odd request for a reply. Note also that 回报 skews formal and slightly written; in casual speech people say 报答 for the emotional sense.