Formal:
* 很高兴能帮到您 (hěn gāoxìng néng bāng dào nín): This literally translates to "Very happy to be able to help you." This is the most formal and polite way to say it.
* 很乐意为您效劳 (hěn lèyì wèi nín xiàoláo): This means "Very happy to serve you." It is also a formal way to express your willingness to help.
Informal:
* 不用谢 (bù yòng xiè): This means "You're welcome" and is a casual way of saying "Glad I could help."
* 没事 (méishì): This means "No problem" and is an even more casual way of saying "Glad I could help."
* 很高兴帮到你 (hěn gāoxìng bāng dào nǐ): This is a more casual version of the first formal option.
More specific:
* 我很乐意帮忙 (wǒ hěn lèyì bāngmáng): This means "I am happy to help." This option is slightly less formal than the first two formal options.
The best choice will depend on the situation and your relationship with the person you are talking to.