How old was Joseph when he helped to interpret the dreams of the baker and the butler when they were sent to prison?
To answer this question you will need to perform some basic mathematics.
First, you know when Joseph stood before Pharaoh and was promoted to be second in charge of the land of Egypt that he was 30 years old .
This is found in Genesis 41:46 :
And Joseph [was] thirty years old when he stood before Pharaoh king of Egypt. And Joseph went out from the presence of Pharaoh, and went throughout all the land of Egypt.
Genesis 41:46
To calculate how old Joseph was, you need to read the end of Genesis 40 and the beginning of Genesis 41 :
Yet did not the chief butler remember Joseph, but forgat him.
Genesis 40:23
And it came to pass at the end of two full years , that Pharaoh dreamed: and, behold, he stood by the river.
Genesis 41:1
Then spake the chief butler unto Pharaoh saying, “I do remember my faults this day…
Genesis 41:9
When Joseph interpreted the dream for the chief butler in prison he did not remember him after the third day when he was released. It wasn’t until a further 2 years later when Pharaoh had the dream that he remembered.
If Joseph was 30 years old when he was brought before Pharaoh, and the dream of the chief butler was 2 years prior, then simple math would deduce that Joseph was 28 years old when he was in prison with the chief butler and baker.