Does anyone know how to solve this?

Need help.

Problem 1.

9/10 of the weight of a loaf of bread comes from the flour used in making the bread. If 2/9 of the weight of the flour is protein, what fraction of the weight of a loaf of bread is protein?

I do not know how to solve it.

And i do ot know what it means.

If anyone helps, i want to thank them in advance.