Please help me with algebra 2 word problem!!!

The lens equation (1/p) + (1/q) + = (1/f) relates the distance p of an object from a lens, the distance q of the image of the object from the lens, and the focal length f of the lens. What is this distance of an object from a lens if the image of the object is 7 centimeters from the lens and the focal length of the lens is 3 centimeters?

If you could do that, then I applaud you.

I've been trying to figure it out but I'm so confused.

Please show me how you did it step by step

Thank you to anyone who tries! :)