Question

Tamera texted a photo of a dolphin to 5 friends. She asked her 5 friends to text the photo to 5 more friends. The photo chain continued with each friend texting the photo to 5 friends. How many photos of the dolphin will be texted after 4 rounds? Write and evaluate an expression that shows the number of photos.
Ms. Sue
I could find the answer -- but I don't know how to write the proper expression for it.
Amy
Ok thank u