投桃报李的翻译是：你帮我挠痒痒，我也帮你挠回去？

You scratch my back,and i’ll scratch yours.

You scratch my back and I’ll scratch yours

英文解释
One person helps another on condition that the second person helps them in return; used to tell someone that if they help you, you will help them.

中文解释
You scratch my back and I’ll scratch yours 字面意思：你帮我抓抓背，我也帮你抓抓背。引申：你帮我，我也帮你。互惠帮忙；照顾那些照顾照顾你的人。

人们会说you scratch my back and I’ll scratch yours来描述一个人帮助另一个人的方式，因为他们知道那个人也会帮助他们作为回报。

除了这个接地气的表达，还有来自官方的翻译是：Giving a plum in return for a peach

投桃报李

“投桃报李”源自《诗经》，意为你赠给我木桃，我回赠给你木李，泛指互赠礼品、礼尚往来，即用礼物为载体，传达对方的善意，表达与对方永结友好的诚意，隐喻平等互惠的关系原则。

2020年3月，习近平在同沙特国王萨勒曼通电话时表示，中国发生新冠肺炎疫情后，你第一时间向我表达慰问和支持，沙特政府和各界纷纷伸出援手，向中方提供了多批物资援助，中方铭记在心。中华民族是懂得感恩、投桃报李的民族。实际上，中国始终在力所能及范围内为国际社会抗疫提供支持，共同维护全球公共卫生安全，正是这一理念的有力印证。

Giving a plum in return for a peach

This idiom comes from The Book of Songs. It indicates an exchange of presents to express good faith and friendship. It also refers to equality and reciprocity.

In March 2020, Xi Jinping said on the phone with King Salman bin Abdulaziz of Saudi Arabia: Following the coronavirus outbreak in China, you expressed sympathy and support to me at the first opportunity. Your government and your people have offered help and provided material supplies to China on more than one occasion. We will remember this. We Chinese people are a grateful nation and will repay your kindness.

On the part of China, it has done all it can to assist the international community in responding to the pandemic and protecting global public health. This is just another example of acting on the idea of “giving a plum in return for a peach.”

来源：当代中国与世界研究院