The last number will either be 5 or 0. For example 15, or 20.
ANSWER
E. 10 and 640
EXPLANATION
The given series is

To find the first term of the series we substitute i=1 to get,


For the last term of the series, we substitute i=4 to obtain,


This implies that,

Therefore the correct answer is E
Jen has 6 crayons
Lisa has 3 crayons
Max has = lisa +1 = 4 crayons
Jen + Lisa + Max = 6+3+4 = 13 crayons
Answer: 13 crayons