Find the infinite sum of the geometric sequence with `a = 4, r = 2/5` if it exists.Give your answer as an integer or reduced fraction.

 `S_(oo)=`  

Get help: Video

Box 1: Enter your answer as a reduced fraction (like 5/3, not 10/6) or as an integer (like 4 or -2)
Do not enter mixed numbers
Enter DNE for Does Not Exist, oo for Infinity